The patterns I chose to do were simply based on casting on roughly 36 stitches so that I had a 7 inch square but not much larger. My preferences is to not have a huge cloth at the end.
I started out with http://handmaidensheart.blogspot.ca/2010/03/scrubby-nubby-dishcloth.html as my first one. I decreased the cast on stitches to 36, using a US size 6 needle and I used a bright green Bernat Handicrafter Cotton. ( I lost the label so the exact name I don't know)
Second pattern is http://homespunliving.blogspot.ca/2010/06/aunt-may-dishcloth.html
The third dish cloth pattern I used is http://www.ravelry.com/patterns/library/fabric-stitch-dishcloth
And the last one I did (which is my favorite)