I usually know what look I want to go for because either the pattern or the fabric "talks" to me. Do you have a fabric in mind? One of the tips I learned is that blocks that have the same number of divisions can be used together and when they are alternated, they form a new pattern.
If all else fails, do the eeny-meeny-miney-mo count off and pick one. Don't worry - the others will still be there with a few new friends when you get the quilt done. :wink: