BPF gets my vote for the most succinct and important piece of advice:
Finally the most important thing for the landing is that the aircraft touches down in the correct nose high attitude. If you are a little high and the aircraft drops the last foot with a bit of a thud, but in the correct nose high landing attitude, that is still a acceptable, safe landing. What is not acceptable is a flat landing where all three wheels touch at the same time or even worse a nose wheel first landing.
I'll add this:
as you fly the approach look at the picture of the runway, then glance at the asi, then the picture, then the asi - alternating about every 2-3 seconds. You can say out loud "picture, speed, picture, speed, picture..." if it helps. You must nail the approach speed that you have previously elected to fly the approach at, to within +/-2knots using the pitch attitude of teh aircraft. and you must use power to keep the picture right. (cue for debate about point and power, but I'm talking about typical single engine PPL trainers). Keep doing this right down until round-out height.
The advice about looking at the far end of the runway as you round out is spot on too. In tandem seat aircraft the instructor can tell when the student is getting this bit right because he can see from the back that the student's head moves fractionally as they change where they are looking. (OK that only works in aircraft where the instructor sits in the back).