Homebrew PCBs

Hi everyone. I purchased some press and peel Blue, and tried the first
board. I was not real pleased, but I am SURE it isn't the products fault. I
used the iron on the TOP of the mask plastic. I noticed that the center of
the board was not very good, but the outside edges were distinct, and sharp.
I was applying pressure on the board with the iron, and used a sheet of
paper on the top so that it would move freely.

I was wondering, should i pre-heat the board BEFORE I apply the
press-n-peel? Should I heat the board while I have it on TOP of the pores
and peel, or should I not press as hard as I did to make a good pattern turn
out on the board?

Thanks in advance!!

Kim