For sci-fi, I'd offer two things for consideration:
- alien names should follow the same rules (phonological, structural, semantic) within a species;
- avoid alien words unless they're needed (the "call a rabbit a smeerp" issue).
Apart from that, I tend to avoid too obviously meaningful names, but I like a name to be evocative -- the problem being, one's never sure a name evokes the same thing to the reader than to the author.