The most important thing is to use a sulfate-free shampoo and conditioner. Shampoo / conditioner with sulfates is very harsh on the hair and strips it of its natural oils, making it dry and more brittle. Depending on your hair type using a hair oil (or argan oil, coconut oil, etc.) on the middle to ends of your hair (not close to the scalp, it'll make it look greasy) after you get out of the shower and your hair is just slightly damp, mostly dry, can help keep it properly moisturized and strong. If you have super fine hair an oil will likely be too heavy, so look for a styling product designed to moisturize, like a cream or leave-in conditioner.