Focus on tight movement, Squeeze your butt, squeeze the bar, and avoid arching. YELLOW and ORANGE can build weight as proficiency allows. BLUE and PURPLE+ should push to end at a heavy weight. With any strength movement, the early levels are really focused on familiarity, getting reps, and staying safe. The ability to produce tension is a skill, and comes with time and repetitions.

We want as straight a bar path as possible, and that goes for all barbell movements. The reason for that is pretty obvious, but any horizontal movement wastes energy, and can also decrease leverage (a bad thing). With the press specifically, because the head is in the way, it can be a little more tricky. To avoid catching one on the chin, move your chin back, away, from the bar when initiating the press, then as you are locking out the bar push your head back through to finish the press and get into a stable overhead position.