To make your hair to stay up straight, you need to trim off the split ends. Also, make sure to wash it with mild shampoo and good conditioner for the type of your hair. After washing your hair, blow-dry it by using hot setting on all of your hair to accelerate the drying. When hair is about half dry divide it into sections so you can concentrate the blow dryer and brush on one area. Once hair is mostly dry, reduce the heat and add a nozzle. Start from the roots and follow the brush down, keeping the hair taut but not stretched too tightly.