I used among other things this --
TEARA VE Technician Study Guide. It helped me quite a bit. I also had a Now Your Talking (I got it years ago at Radio Shack).
Here is a hint that I did. Take a couple of index cards, and make flash cards. I did things that are a little harder to remember, like OMS Law, frequencies, symbols, formals for the di-poles, etc. I was studying with my flash cards right up to the end.
I took my first practice test cold blind (never even have studied anything) and passed it. When I took my test I ACED it, only almost missing a part 15 question. One thing is to read the question and answer very carefully. The only question I had trouble on, and caught myself was T5D09. I paid attention and got it right. One thing is just take your time.
As for in our Club -- we have a 19 year old girl, who has had her EXTRA, since she was 9.