Another small point - always try to have your seat in the same position. I know it sounds silly, but you are aiming for consistancy & this is another variable you can eliminate.
Altering the seat height will change 'the picture'. If your instructor wants you to put the top of the cowling on the end on the runway when you flare and the seat is right down, you won't flare much.
Conversely if the seat is up, you will have to flare more, which is a good thing, as long as you don't balloon!!