I PP one log cabin because the block was 5" and it had squares going diagonally across the block (sorry can't remember the name- lightening strike?) I needed the help for that small of square.
But other than that I have just picked a size of strips and went for it. The size is up to you, and the number of strips in each block is up to you. Start with a square, 4 patch, 9 patch, then strip around it. It can be relaxing to do.:)