okay here's my advice im no expert but I used to be a boxer, your power comes from your shoulder, you need the proper stance when you punch move your hips towards the punch, Alaways keep your hands up oh yeah punching with light weights in your hands is good, and when shadow boxing you always wanna aim taller then you that way if you fight some one big your already used to punching high. Oh yeah boxing is very different then street fighting! Boxing is skill, fighting everything goes head but his ass they least expect it! try it.