You need to first decide if you want to do the traditional TB that has the set in Y seam or the "not your grandmothers" tumbling block that does not have a set in Y seam. Here is one from Quilters Cache that does not have a set in seam and is PP
http://www.quilterscache.com/T/TumblingBlocksBlock.html
Patterns are available all over the internet. When I made mine I did the traditional set in seam and used the pattern from the book Quilts! Quilts!! Quilts!!!
Then you need to decide what colors you want and should choose a light medium and a dark in that color scheme, or you could go with all different colors but just stick to a light a medium and a dark. The contrast gives the TB that wonderful 3D look.