Can't live with 'em, and can't live without 'em.
You've got these aliens, or weird creatures, or futuristic humans, and you don't want to call them Fred. Fred doesn't seem to fit into your world- building concept; it's just a little too retro.
Well, maybe and maybe not. Remember that even in a far future story, you're translating into 20- or 21st-century English (or Spanish, Russian, or whatever). So it's not always a bad idea to use common names. But sure, use futuristic names if you like, and for your aliens you want to come up with something that sounds, well, alien. The same may be true for your place names.
But, remember your poor reader, who just might want to say the name out loud. You tell me — how do you pronounce Xblmrph?
So make up names to your heart's content, but make
them pronounceable. Don't just string together a bunch of consonants and say, Whoa, alien! Try them out and see if you can pronounce them.
Another pitfall in names is this: Don't give two characters names that look or sound alike! Unless you're doing it for comic effect or another very specific reason, you'll only confuse your reader. As the author, you might be able to keep your characters Rob and Rod straight in your head, but don't expect your readers to be able to. Even Margaret and Mable could give trouble.
At the risk of being dogmatic, I would even say, start every character's name with a different first letter. Give your readers a break today.
