Hyper-pigmentation? HELP!?

Overall, I'm fine with my skin. It's clear and even for the most part. SOME places like my underarms are a bit darker than the rest of my body. What can I do to get rid of this? I've tried lemon, Ambi, Palmer's Bleaching Cream, etc. Give me suggestions that'll ACTUALLY WORK & that may have worked for you. Thank you :)