Good advice given so far! I would add just a few other suggestions.
First, handle her feet often, not just when you want to trim her nails. If she doesn't like it, just start with a light, brief touch or one-finger stroke. Over time, she'll tolerate more. If she's used to having her feet petted, stroked, squeezed, and manipulated, it will be a lot easier to proceed to the next step. Wait until she's comfortable with this before trying to trim. BTW you can start at any age; my two youngest got their first trim when they were tiny, probably 4 or 5 weeks. Little kittens have *very* sharp claw! (And they don't know enough to argue!)
Second, wait until she's very relaxed or asleep. That's how I do mine. I keep clippers all over the house just in case I get an opportunity!
There is no rule that says you have to do all the claws at once. Just one or two at a time is fine! Just remember (more or less) where you left off so you can proceed to the next toe.
If the cat struggles, let her go. Never make it into a battle. If she feels like she has control over the situation, she will be more relaxed each time. If she's having a bad day and just won't have it--chill! It can wait until tomorrow!
Trim only the sharp tips of the nails. If you even get close to the quick, she will feel the pressure and resist. As you both become more comfortable with the procedure, you may be able to take a little more, but the main thing is to make it totally painless and as stress-free as possible. Also, not all cats' claws are clear so the quick can't always be easily seen. Err on the side of caution. If you ever cut the quick, it will be the last nail you ever trim on the cat!
Claw-trimming basics (with illustrations) can be found at:
http://amby.com/cat_site/cattrain.html
Cheers,
Dr. Jean