Hair advice please

My cat was a feral for 3 mos and caged at a rescue location for 3 mos. The volunteers loved her, but had no time for her. She is a 6 mos old petite SnowShoe/Siamese. Her hair looks like it's going to be long. She needs a good brushing, but she won't allow me to touch her yet. OK,so here's the question. What do I give/feed her to promote healthy hair? Thank you