This is a well written "how to land" from the JPO knowledge bank: http://www.jetpilots.org/knowledge_bank/landings.pdf It is worth a read even if you already know how to land.

FWIW, I've had the same problem - first few landings with a new airframe are pretty good, the next 5 or 10 kinda suk. I don't know for sure why it happens, but I sometimes find myself slipping back into bad habits without realizing it. I think it helps to consciously focus on the fundamentals every second of every landing.