Just wanted to add briefly - First, knowing about the straight of grain is probably one of the most important pieces of knowledge - your blocks won't stretch. Pins, starch, and my iron are my best friends. I pin, no matter what - it keeps things from moving. I remember Fons & Porter doing a segment about triangles and the importance of knowing which side has your bias cut side. That made triangles go together better - less stretch - and starch when pressing!
To help w/ my 1/4" seam allowance, the magnetic seam gauge that I bought at Joann's is essential to helping me keep a consistent seam allowance.