Popular baby names lists should be perused, but for the opposite reason for which they are compiled: to show you what you should not name your child. Avoid giving your child any name in the top ten or, ideally, the top twenty. I personally have known at least eleven Jessicas.
Cutesy alternate spellings are to be avoided. To paraphrase a writer whose name I've forgotten, if you absolutely must name your child after the northwestern region of France, use the correct spelling, not Britany, Britney (only Ms. Spears can be named that), Britni, or any mutation thereof.
Unique names have their appeal, but decide whether you want everyone your child ever meets to demand an etymologic lesson. Just ask anyone with a rare or one-off name; they will tell you they are tired of having to explain their name to nosy strangers and deal with the "that's so unique!" and "what were your parents thinking?"-type comments.
Children should not be named after places, whether cities (Paris, Brooklyn, London, etc.) or countries. India is especially to be avoided if you are white. Hasn't colonialism done enough already? Why besmirch India's legacy and cultures by naming a spoiled hipster child after it?
Children should not be named after old-timey professions (Cooper, Mason, Chandler, Apothecary).
Don't Frankenstein names to create new ones. Some examples from Pinterest: Linley, Oakleigh, Saylor, Jaylee, Deagan, Adaley, Kanon, Brynlee, Kastyn. W T F
Do not use common nouns or adjectives as names (Apple, Bruin).
Avoid giving your child a name from a song, especially a popular, well-known song (Roxanne, Jolene, etc.). Probably the only annoying thing about my name is that people will sing "Michelle, my belle" at me from the Beatles song. I do not like it when people do that, although I do like the song.
Similarly, think before naming your child after a book you love. Some names are timeless and don't stick out (Jane, Elizabeth, Harry, Sam), but others fall into the faddish category (Katniss, Hermione, Atticus, Huck). It will be hard or irritating for your child to be constantly compared to their book character; they can never get away from it, because they are clearly named after a Harry Potter book or whatever. Take especially great care when choosing Shakespearean names. Imagine your child's disappointment when she discovers she is named after a girl who killed herself over a boy. Also, a lot of Shakespearean character names are weird (Hero, Hamlet).
Great care should be taken when choosing animal or fantastical creature names to name a human child. (I wasn't even going to put this but someone on Pinterest named their kid Griffin.) Plant names are typically easier, but again, be reasonable.
Surnames should not be used for first names. This confuses everybody. If you want to name your child something that ends in -son or -ton, don't. (Jason is acceptable.)
Faddish names of all stripes should be avoided.
Bible names are acceptable, as long as they are reasonable (see first opinion). Rebecca is fine; Joktan is not. Don't saddle your child with an obscure name in a dead language that no one can pronounce. It is the 21st century, and I think we can all agree that the Puritans were ridiculous.
For the love of everything, do not pick a random word from a language you don't speak for your child's name, especially if that language is from a culture you are not a part of. I have a friend whose classmate named her child Tarea (homework) after a trip to Mexico, only learning afterwards during a Spanish class what it meant.
Naming children after older relations is sweet, but you don't want your family tree to look like a Gabriel Garcia Marquez novel. It gets confusing. If at least two other family members have that name, reconsider.
Try to choose a name that will yield the least possible amount of teasing. There currently exists no name that cannot be twisted into mockery by children, but try to minimize the vexation as much as possible. My own name yielded only minor "stuck in the well"-type rhyming.
If the only other people who share your child's name are retired and grey-haired, it is an old person's name and should not be given to children (see first and previous opinion). If a name is truly timeless rather than dated, you should be able to find people of all ages who have that name.
Consider that you are giving a human person their name. This is the name they will carry for their entire life (unless you do such a bad job they want to change it when they're older). Give them something worthy, not thoughtless or absurd or boring or commonplace.
unknown provenance, via Tumblr
EDIT: Another thing to consider:
