Start by taking everything out. Starting with a clean canvas will help you prioritize what should go in. Try to eliminate what doesnt fit or what you have not worn in more than 6 months.
Try to get rid of old shoes and clothes before putting everything back in.
Whenever you have a limited closet space, its ok to use shoe hanging units on your wall.
Jeans are always easiest to maintain as a folded item. When possible hang your shirts.