the thing that i do is to just start from the ground with your knees and then you will build enough strength to do it with out your knees ... thats how i learned from when i was little …lol and you can try to go into a real push up position and bend your elbows a little and try to hold yourself up as long as posible and then you can work on trying to take it slow to go lower and lower trying to hold your self up...
but one of the importend thing is to work on it! when i was 12 years old i could do 120 pushups non stop… cause everyday i would do push ups… like i would do the first month 20 push ups then the next 2 weeks 25 push ups then so on ... and i did that for a year... because my teacher was in the army and wanted everyone to do push ups ... and then i went to hand stand push ups!!! lol but i have to be agents the wall or someone holding my ankels …lol but i think its all about balance ... because i can do a lot of push ups but cant do one, one handed one ...lol