First and foremost, to improve your credit score you should eliminate debt. Stop using a credit card for purchases or don’t just pay the minimum balance at the end of the month, instead pay the whole balance. If you are not capable of paying the whole balance, then cut your credit card in half because you are living beyond your means. Try to avoid opening up store cards. Many department store offer incentives and discounts that lead us into getting a card, however the interest rates are outrages. If you have newer cards, close them, but keep the older ones even if you choose not to use them. What affects your credit score positively, is the length of your credit history.
Everyone is entitled to receive one free credit report a year. Review your credit score annually and take the necessary steps to improve it.