The Log Cabin is an easy one and like the Rail it has lots of possibilities. It can be scrappy or not. The main thing is lights and darks so that a pattern emerges from the contrast. It is my understanding that by tradition the center block or chimney is either red or yellow. Once all your blocks are made, it is fun to make different patterns by changing the direction of the blocks. Here is a link for one log cabin.
http://mccallsquilting.com/legacy/v21_pattern/