ok say if you start one arm pushups with left hand..
now kick out your right leg to the side on the floor and up AGAINST a wall or door ALSO keep right arm on thigh for support, this gives the support needed in order to maintain balance. especially if you are a big man youl be lucky to get a half one arm pushup. with this youll crucify all the upper body muscles on your left . when doing the pushup just go down as far as you feel safe too. eventually you will progress if you do this everyday and eat like me and drink plenty of water like me
but this form/techniqe will get you on the road of really teaching your body to use the abs chest and arm all at once without injury