Spending time abroad is definitely personally enriching, as well as being an important part of broadening your focus, and the Ph.D. and postdoc periods are the best points in your career to do this. But just what is involved? Of course, the academic, educational, employment, and cultural systems will differ substantially from what you are used to at home. Well, this is sexy after all, isn't it? It's one of the reasons why you're thinking about going away in the first place. No question about that--enjoy the change to the utmost!
During my graduate, Ph.D., and postdoc periods I spent time in the United States, the United Kingdom, and Denmark before returning to an industry research job in Germany. And that eventual return was always at the back of my mind. Some people worry that spending time abroad means losing touch with developments at home. But it doesn't have to be that way. Just as in Part 2  I suggested developing different interests in parallel with your main research focus, so is it not only possible, but advisable, to keep an eye on your home country whilst getting to know a new culture and approach to science. No matter how tempting it is to stay abroad, and how far off resettling in your home country appears to be, never mentally leave home, but rather enrich home while abroad.
What do I mean by that? In short, try to do things abroad that are not only of value in and of themselves but that are also of value back home. So if you are still undergoing education or training, see to it that your courses match your degree/credit system back home. Fortunately, the Bologna protocol will make life easier in this respect. It rules that, as a default, degrees from accredited institutions can and should be used as they are. So, if you are, for example, Mr. Tony Template D.Phil. (Oxon), * this will stay as it is and not be "translated" or "transferred" in any way to a Ph.D. or other doctoral degree name. ** So check with the appropriate authorities whether the foreign institution (and the degree programme you wish to pursue) is accredited. Meanwhile, if you wish to be conferred your "home" degree as well, check if there is such a thing as a dual degree programme, where two degrees from two universities in two countries are conferred in one integrated programme of study; more and more of these dual programmes are being developed and offered. Additionally, under the Bologna protocol, higher degree paths are supposed to become harmonised, so that with your M.Eng. from Country A you should be directly eligible for Ph.D. studies in Country B. This must again be carefully verified beforehand in each individual case.
Make sure your sought-after qualification is actually worth something. Oxford University, after some years of waiting, automatically confers a Master's on anybody who holds an Oxford Bachelor's degree on the basis of its assumed supremacy. In other places the highly prized MBA is given away after passing an academically poor programme. Employers are aware of these traps, so you must be, too.
A quite different story is the transfer of individual credits. Again, the Bologna protocol recommends that universities all over Europe use a U.S.-style system of freely transferable credits, like ECTS (the European Credit Transfer System), used since 1985 under the ERASMUS programme. (For an overview of the discussions surrounding this so-called European Higher Education Area, see http://invest.ugr.es/guia-t/EspacioEuropeo/godmine.htm .)
Unfortunately, reality has not yet caught up with recommendation. Faculties still discuss the number of credits to be assigned--if any--for courses, mandatory practical experience, or industry work in each individual's case. Even formalities are discussed: Is an unsigned computer enrolment an official document? Is the same grading system used?
So get in touch with the relevant offices at your home university while you are still abroad and present credits and work experience certificates to them for acknowledgement. They might be willing to give you credit provided that you add small items here and there (Germans: Get stamps and signatures; Italians: Enrich your certificates with superlatives). These requirements can easily be explained to your employer/professor while you are still abroad, and most people are willing to accept such cultural differences and adhere to your home rules in order to smooth the path for you. However, all of this gets much more difficult if you are confronted with these issues once you are back home, especially if some time has elapsed.
If you are working, make sure that your employer assigns projects to you that are also well regarded back home. Ideally, you will work in a multinational company that uses the same standards everywhere. But be aware: If it comes to a comparison, that real estate deal you brokered in New York will be more highly regarded than the one in Tibet. So if you happen to love your work in Tibet, a way to achieve status is to engage in a multinational project involving many partners (difficult, I agree) or to actually manage the project in Tibet in the same way you would manage it in New York.
A well-organised, well-documented project plan and a professional presentation always speak for you, so adopt that working style, even if it is not required at your current site. If you have any influence as to which projects you are actually assigned to, or even the opportunity to propose your own ideas as projects, use it. When doing so, call that old friend back home who has gone straight into a job and ask how a project on topic X in style Y with partner Z would be regarded. You will receive inside information about the value of your work from the home perspective before it even gets started.
Lastly, collaborate. Even if you are still a student, take the ambassador's role. Because you know (and if you don't, find out!) what your department at home is doing, it is very easy to identify common projects that link the specialities of your host and your home institution. I used this method once by simply presenting somebody else's results, with his consent and enriched by some of my own results, at a workshop back home. I knew that the topic would be of interest there but that the workshop organisers could not afford to pay for the author's attendance. Instead, they saved money by funding my, much cheaper, travel. Think about it: By bringing two experts together and adding some of your own thoughts and some diplomatic work, you will be part of a project/publication with some 20% of the total effort, say. Mostly, this is not regarded as parasitic behaviour. Quite the contrary: Most researchers are extremely busy and will not readily have time to establish new co-operations, even though they regard them as very valuable. You are helping them achieve exactly that with less effort on their part. In return, one of the partners may later be happy to serve as a personal reference for you--the highest impact door opener! (Sorry, but the importance of these contacts cannot be mentioned often enough!)
Many times, such collaborations have far-reaching effects for your future career. Small collaborative projects often act as nuclei for long-term projects, eventually resulting in common proposals to supranational funding bodies. Remember, the European Union requires that there be participants from at least three member states to even file a proposal. And, finally, if the time has come for your job interview, a high-ranking international referee is of high impact (as is proof of a visible common project). Indeed, this sort of reference is even essential in some cases (professorships in Germany, many top international jobs). The message is: The references you will need at a later stage of your career have to be grown--and at an early stage this can be done very informally, out of common interests or with limited resources. The other message is that even without being parasitic, you do not have to do all the hard work yourself.
Although there are certainly many positives to living abroad, one shouldn't ignore very personal feelings such as homesickness, or what we might call "aerophobia": the aversion to constant air travel and being away from home. Keeping professional contact with people at home as discussed above can help, of course, but there is no sure-fire remedy. If you are the type of person who clings to the home backyard, I must say science is not for you. If, however, you occasionally suffer from these feelings, be assured that this is quite normal.
What I can contribute from my own experience is sort of an anchoring through cultural stability. It is extremely helpful to volunteer to others insights about your culture. In the United States, I organised little parties with food from home. They were great dos--it became established that anybody who was travelling was to import some favourite food for these parties. The response to such little actions (performing Christmas carols, watching national football games) is overwhelming, reflecting a common desire in your compatriots for some "anchoring" and an interest on the part of the surrounding "foreigners" in your culture. The roles are reversed: For this evening it is you who sets the cultural standards and the others who adapt. In return for these initiatives, your cultural identity strengthens, which is especially important while abroad where one can easily feel lost. In contrast, any action that isolates you is dangerous: Endless phone calls home, spending time staring at photos or reading old letters, or recalling memories from back home may easily drive you deeper into a problem. Rather: Open up!
Of course, you may never suffer serious homesickness, but in any situation it is better to be proactive. Should your personal situation become unbearable, do not feel obliged to pursue your objectives at any cost. Fly home--for a vacation, work report, conference, or the like (as I did; see above)--if possible, and if the worst comes to the worst, terminate your stay abroad. Under such circumstances, as long as you have maintained your home contacts and kept your professional interests broad, even what could be perceived as a failure need not be terminal to your career.
In today's climate a scientific career may not be an easy choice, but it is still a rewarding one. Indeed, if you adopt a career strategy in which you constantly seek to broaden your experience, whether culturally or scientifically, you may find not only that your career takes you exactly where you want to be, but that it's a place you didn't even know existed when you set out!
* In case you are puzzled, this is the official doctorate degree from Oxford University, U.K. They don't confer Ph.D.s there.
** However, degree transfer still exists in some countries--check with your local authorities.