what programs are you using? what sizes (in pixels) are your pix? any more detail might help.
The briefings and tutes I've seen use pix that are often displayed at 128x64 pixels, or any multiples of 2 (177 x 88, etc). Often your orig source pic has to be big, say 1024 x 512, and then reduced when displayed, otherwise you get pixelly fuzz. I found 256 x 128 too large, 128 x 64 a good size.