How should i do push-ups? Need advice?

what we do is practice good posture if u have a long mirror do them in front of it so u can make sure you keep your back straight with your body. its not about how many you do but the ones done correctly lower yourself till your arms are parallel to your back which forms a 90 degree angle. to help build muscle core you can practice holding it in the down position for a few seconds. do your max before and after every meal and before and after bed.