Xing Yi,Fa jin, Punching power?

I'm a practitioner of the Big three, Taijiquan, Xingyiquan, and Baguazhang, I can say that you shouldn't rely so much on your arms for the power, use the arms to keep the punch solid, but focus on generating most of the force from your back leg. Additionally, Momentum is a significant factor behind the blows, Xingyi utilizes some charges that give the extra strength, a charge's force is determined by weight and size, so, if you're a small guy, the charging strikes of Xingyi won't work that well, if so, use mostly still techniques. Not many other tips can be given because someone's ability to utilize the force depends mostly on themself and how you utilize your body well.