WOW!! As a newbie to the board, what an amazing number of responses to someone's question! I can't believe how lucky I am to have stumbled onto this board!!!!
To the OP - I've only ever sewn one quilt from a pattern, the rest I've simply looked at pictures and devised my own pattern. The trick, as people have said, is to look for the "repeating block" ... Once you have that, it's a piece of cake!
Paper and pencil are awesome! Once you've drafted it sew a block with scraps and see how it turns out ... then you'll know if you want to adjust once of the "pieces" from 2 inches to 3, etc.
Have fun!!!!