The best way to start as a beginner is with half square triangles. There are so many ways to put them togather to make a block.
If you use El Burns patterns you will always have a perfect block. She oversizes so you square up to the perfect size block. She also has you square up each section of a block so that every piece is the right size as it goes togather.
I have never had a problem with her patterns. To top it off she always has the simplest method to use.