Do not study the states + capitals you already know well. Try to focus on the harder ones, and try to make up fun ways to memorize them. Like, California, Sacramento, Albany New York! Helena Montana, then the Olympic games. Olympia Washington Carson city Nevada! Phoenix Arizona, Sante Fe New Mexico, then we go on to the southern states! Oklahoma City, Dallas Dallas Texas, then we go over again! etc. etc. Try to find the tune i am using. I know, it is corny, but try it!
theres a song about them called fifty nifty united states. it is kind of annoying but deal with it. there are some online games that help you with that because those helped me with my tests about the states