assuming you have printed on the proper side of the paper transfer. each type of paper have its own specific temperature needed for the transfer to occur. what is actually happening is that you are printing the side of the paper coated with a polymer substance (normally in mirror image, except for one step darks), let the ink dry for approx. 15 minutes, trim the unwanted portions of the paper. ( while you are pre-heating your press) Depending on the press, it normally takes between 30 - 45 minutes to properly heat up the press to operating temperature ( use an IR gun to verify the temperature of your platten). Also depending on the paper, temperature for transfer range from 300-400 degrees F. Paper from walmart normally transfer at 350,
JPSS i believe are 375. Also depending on the paper, dwell time ( time the press remains close) range from 10-30 seconds ( some special papers up to a minute). And also depending on the paper, either peel it while its hot or peel it when it cold ( the backing paper). The instruction should have came with the paper. If the paper is too old and has been exposed to the atmosphere ( moisture), do not expect it to yield a good result, you use the batch for practicing though. Good luck.
step by step directions on making transfers? 
Daniel Slatkin, 
