i have three cats. mamma and her two girls. one is extremely timid and scares easily. it took one year of petting and talking calmly for her to let me even pick her up. now we walk around the house a bit and i let her down easily. when she was younger she bit me twice but was extremely frightened at the time. still, i don't want her to get so scared that she bites or scratches me now. so i give her lots of loving her way.
good luck.