It is important to understand the difference between practice and warm-up. Practice is where you work on your swing and it can be very technical. Warm-up is stretching your muscles, getting loose and ready to go.
For practice to be effective you need accurate, immediate feedback. This could be a teacher, training aid, video or something else. All research shows that those who use feedback get better quicker. You need to create good habits and you can't control them by feel alone.
There is a difference between deliberate practice and ball bashing. Deliberate practice is highly demanding, it's not much fun and needs to be done on a regular basis.
You should learn the game from the green back to the tee. You learn to crawl, then you learn to walk, then you learn to run. You learn small shots, then you learn bigger shots, then you learn full shots.
It's critical to understand every shot has a target and therefore a target line. Everything you do must have a relationship to the target line. To really hit a controlled, pure shot you need to swing, turn, shift in the backswing then shift, turn, swing in the downswing.
It's important to keep your grip pressure constant from start to finish with cheap Titleist AP2 712 irons. A good quote to remember for the full swing is "feel the force, not force the feel'.