I disagree with picking a name from popular baby trends of upper class people in the 90s to name a teenaged girl now. If you are writing a period piece, then do research on names of the day, but I think most modern fiction set in the current time chooses more current or pre-current baby names. Teenagers and grown-up characters often have way cooler names than their parents would have realistically picked out, names that aren’t even cool yet now, and stick in the minds of readers as cool names, not names that are already dated by the time they pick up the story to read. Depending on how the character needs to be portrayed, certain aspects given the name, like a name that doesn’t seem to fit her personality very well might make a good contrast.
I think the name a person has tells about that person’s parents and upbringing more, so much more than what a character is like, you might want to outline what kind of people her parents are, the parents of her friends if she has friends you need to name as well - some people will be very classic, some overly trendy or weird or eccentric, so don’t name them all like they have the same parents with the same preferences. If you name any of the parents as well, I think a believable set of characters has believable choices made - parents with kind of boring names might go overboard on eccentric names and vice versa. For parents’ names, you would do ok consulting lists at the ssa.gov site, lower-left side scroll down, input a target year (http://www.ssa.gov/OACT/babynames/) for the year they’d have been born for believable names to fit their age - considering that some of their parents (we’re getting very far away from the main character at this point) would be strict or old-fashioned also - they wouldn’t have all been given popular 60s or 70s names.
I don’t write, but something I would draw out for myself would be character bios and at least some sort of family tree. You don’t have to name all the parents of each friend but have some idea why the friends might have their names, and possibly a stand-in name for their parents that’s never mentioned in the story, you know, estimate what their name probably was to shorthand their personality and why the characters who are peers of your protagonist have their personalities and names that fit - sound believable, but I think in the mind of the audience, which I would suppose is your age, would like characters with names that aren’t contemporaneous with their own.
I think [name]Sydney[/name] and [name]Shay[/name] might be ok. I think [name]Memphis[/name] is too distracting and not that lovely. If you are reading a character on every page, the name should become more complex and beautiful (in some aspect) every time it’s written. By beautiful, I don’t mean “beautiful” names like [name]Isabella[/name] or [name]Priscilla[/name]. If it is not a common name, by the end of the story, it should seem like the most sensible choice. For example, before [name]Harry[/name] [name]Potter[/name] books came out, I defy anyone to consider [name]Hermione[/name] a pretty name, a normal name of someone you might meet under the age of 75. And yet, over knowing the character, could her name be anything else, and doesn’t it appeal to lots of people now?
The name or names you choose for the characters don’t need to be too odd, but you might put some effort to research names that sound a lot newer than when she would be born - go to that ssa.gov site and look for names very low on the top 1000 that sound like they should be popular again soon, don’t worry if they won’t be. Make sure they aren’t just resting down there from recently peaking. Consider the phone book or some genealogy web sites also for some family names that wouldn’t be on the list. That would be very believable to me, and the name would also sound new.
Here is a blog entry made by [name]Pam[/name] a few weeks ago on this topic. Her story is set in the past, so it seems to have a different type of agenda with regards to what was typical or might be believable at the time. You don’t necessarily have to place the story of how she got her name in your story, but it helps if you consider a probable history of what her parents were thinking.