Kaye England has a Nifty Notions ruler for cutting side triangles that are oversized just a little. You look up the size of your block then cut the size triangle indicated. If you follow her method there is no bias on the outside. I also like to lay out my quilt and triangles on a design wall then number each row (block 1 of row 1 etc) I use those round pricing labels in a bright color from the office supply store and write on them with a sharpie. They don't leave a sticky residue behind.