Best way to take care of chemically damaged hair?

Your hair is probably over processed. You will need to back down from all the dye jobs for at least a year. Have a professional trim your ends, then use a shampoo and conditioner which works with damage hair only and has in vitamins. Use it for at least two months. At that point, switch to something that has in less aggressive like a moisturizing shampoo and conditioner. Treat your hair at least once a week to a VO5 hot oil treatment to bring the life back into your hair.