A friend of mine would like to begin learning Moreh N'vuchim seriously and is unsure of exactly where/with what to start.
Start with Pines' translation into English since it's the classic English translation. After that, look at Yehuda Ibn Tibbon's translation - that is the original Hebrew translation. I push the classic sources since they are clear enough to provide a thorough explanation.
The vast majority of the new versions don't add anything to the discussion, other than academic translations. Just keep in mind that those translations are not likely to carry the spirit of the Guide and rather take a critical approach of the Guide itself. It may also be a good idea to do a bit of reading about Aristotelian philosophy as well, since the Rambam discusses that extensively.
Beyond that point, your friend is best off learning Arabic and looking at the original text (most translations in my experience by and large do not reflect the true meaning of the original text - there are nuances in the Arabic that both Hebrew and English cannot express. I say this as someone who deals with Judeo-Arabic on a consistent, weekly basis).
The Pines translation is the best. Better than the ibn Tibbon translation by far. Unless you are history scholar, there is no reason to ever need to read this version. If you want to study it in Hebrew, the only edition worth reading is the Qafih edition. That's actually true of any of the rambam's works.
The best place to start is where the rambam says, not with the guide. If you sit down with the guide without any experience in secular philosophy, you're just plain doing it wrong. The guide was written for the student of philosophy who has difficulty with Judaism, not vice versa. And religious Jews are frequently surprised that a book about metaphysics and philosophy doesn't teach you anything about metaphysics and philosophy. This is why the overwhelming majority of those who have studied the guide didn't understand it.
Before you sit down with the guide, you need a thorough understanding of philosophy as it was understood in medieval Islamdom. Primarily that means Aristotle. You must have an intuitive understanding of Actuality and Potentiality, the Four Causes, and Islamic philosophy of mind with an emphasis on intellect. You must learn to think in these terms as the guide is explicitly written for "one who is inclined to think in a certain way." You will not find this information in any book written solely for the Jewish audience unfortunately. You will need to branch out to secular academia.
He also assumes familiarity with his earlier works, the Mishneh Torah and his commentary to the mishnah. In my experience, you can get by with just the introduction, pre-chapter introductions, and shemoneh peraqim and the commentary to pirkei avoth. This is of course in addition to Tanakh, Talmud, and the midhrashim. However, the Pines edition is well footnoted so you can investigate as you go along.
My last piece of advice is to go exceedingly slowly. Contrary to popular perception, the rambam is not obtuse or hard to understand. If you aren't understanding what he's talking about, it means you haven't done your homework. Put the book down and study the requisite philosophy and rabbinic texts until you are ready to try again. My first reading of the book took three years as I had to go back and revisit the philosophy to understand it. My next reading went much easier because I had developed a personal relationship to philosophy that the rambam was directly addressing.
The best translation (most readable, thus following the Rambam's advice on sacrificing literalness for the sake of comprehensibility) is Michael Schwarz's translation, although R. Kapach's is also useful. I would also recommend the sefer מנופת צוף by R. Yonatan Blass, as well as R. Yitzchak Shilat's בין הרמב"ם לכוזרי.
Translations: English - Friedlander's translation is available on Google Books and on Wikisource. Its easier to read, and includes helpful footnotes, but it might not be 100% accurate. Pines is a very literal translation, but doesn't help you out. Also, he and Strauss had very strange views about the Rambam.
Hebrew - Ibn Tibbon's is the classic one, though people say he didn't do such a great job. Kapach is supposed to be better, and he has lots of footnotes.
Unless you're really into Judeo-Arabic writings, I don't know if it would be worth the trouble learning the original language.
It does make sense to get some background into Aristotelian philosophy, since that's what Rambam is dealing with. Acording to Rambam, you can't just read one part on its own, since you'll need to compare it to other parts. Even so, you might want to start with a more "exciting" middle section over the homonyms section.
I highly recommend learning with the classic hebrew commentaries. the Rambam is writing for a generation highly steeped in advanced philosophy. without commentaries you'll get stuck or misunderstand alot of what he says, especially when he argues on aristotle regarding creationism and God. You might want to check out the shaar yichud for background understanding of much of the premises. available here:http://dafyomireview.com/article.php?docid=398 (this has translation of commentaries with it)
shaar yichud is also a good background start since its very structured while the moreh jumps from subject to subject so you'd need to read it from beginning to end a few times to be able to put things together
I think a great way to begin is by reading this little book: Maimonides: A Guide for Today's Perplexed by Kenneth Seeskin.
I would again suggest the Hashkafah Circle Blog which has the text and the traslation available and in Depth Shiurim as a Starting point
http://hashkafacircle.com/shiurim/category/taamei-hamitzvos-moreh-nevuchim/
