I have a 8 year old mare that we are having problems with?

We started working with her cause she hasn't had a saddle on her in a year and we can't get the saddle to stay on long enough to cinch it. Plus I'm the only one that can get around her and her not panic my dad brother and cousin have tried but she gets spooky. my dad said that she might have been beaten by her last owner is their anyway that I can gain more trust from her where i can get a saddle on her and her not to spook around men?