Making A Pattern

I'm going to be making a knitting pattern soon and I was wondering if I could get some advice on making one. I'm making a dishcloth with an image on it (actually it's a Keywork) using the basic knit and purl technique. What is the best way that I can create this image on the dishcloth without making the cloth look like crap? I have a pixelized PDF of the image, unfortunately I can't put it on my blog for some weird reason. Any suggestions would be greatly appreciated. Thanks!