For longer than I care to admit, my gym goal has been to do a pullup. Since I became determined to get decently strong, I've been haunted by gym class memories- taking wrestling over gymnastics because I was too afraid to go upside-down, struggling and failing to climb a rope, and dangling helplessly from a pullup bar when it came time for the dreaded Presidential Fitness Test. I no longer give a crap about my humiliating volleyball serve, but I'm not giving up on the other things!
If you're a girl, there's really never been any shame in not being able to climb a rope or do pullups. You'd give it a shot, and the teacher would say "that's ok, most girls can't do it." Well, once I got into my late twenties, I didn't want to be most girls any more; a few months ago I climbed a rope for the first time, and last weekend I got my first pullup! I found this article from Urban Gets Diesel to be really helpful; mixing up grips and methods was definitely key. I used assistance bands, did negatives, partials, jumping pullups, and static holds. Once I was strong enough to do one with the smallest assistance band, I made sure to do a couple of those every day I was in the gym, and focused less on using the heavier band that allowed me to do a higher volume. Also, I tried my best to resist the urge to kip; yes, it does make it easier to actually get your chin over the bar, but I've read several sources that state it's safer to hold off on kipping until after you have the strength to achieve a dead-hang.
So keep hangin' in there, babies! For most of us gals, this is something that takes serious werk; it might take two months, it might take over a year (yes, that's about how long I'd been trying). You'll feel pretty bad-ass when you get there, and it's always nice to add something to that list of things you never thought you'd be able to do.