It's a matter of using the right muscles at the right time accelerating them in the right order and timing. It is easy to say and can take a while to get right, especially if one has already been hitting a different way. Knowing what the order is an entirely different matter than actually doing it and it is easy for us who watch a vid and criticize and correct this or that.
A lot of newer players who want to apply extra power often use a lot of their upper body and upper arm (the shoulder area) and in the act of trying for too much power, get too tight and fight against an effective order of timing and use of the muscles. An effective way to get more power it too RELAX more and be more LOOSE, which will help you get a little lower, rotate the trunk a little more and let that torque made by the leg and hip opening explosion flow up the abs and lower back, and turn that into shoulder rotation and staying loose, allow that power to flow into the upper arm and snap the lower arm at the elbow and snap the wrist at impact.
Don't get too bent up by everything and be as patient as you can, it is not something we instantly fix and get right. If you do not have a coach or a better player correcting you on the spot constantly, it is much more difficult, but not impossible to fix. Even with a coach and multiball, single ball, hardcore combination drills, practice match point situations and whatever a coach can help you with... even with all this a player doesn't suddenly fix their form and timing in one day. It takes a LOT of coach telling the player right there and then what they did and what they need to do. Korean coaches in the early stages often go to the player and move the body part for them to give them a feel for what the motion and timing are. You can still do it on your own, but it takes a lot more learning and attention to what you are doing to fix it.
Korean coaches have their players stand for what seems to be 30 minutes or more at a time in front of a mirror while they wait for lessons going over the very basic FH drive motions. Old school coaches are more hardcore about that. It is a good way to get instant feedback and see what you are doing in reflection of that mirror.
Again, until you get this effective way to produce bat speed and power/spin from your lower body on up, SLOW everything down and stay LOOSE. Don't go for the kill or 10,000 rpm spin just yet. Ease it back a bit to where you can control your movements, yet you still gotta be a bit explosive, just tune it down some to a manageable level. You will soon "feel" what is effective if you correct it. You will know a shot had power and you were using much less effort, it is a sign of being more effective on your movements and timing.