Not affiliated, but there is a wonderful book, PERFECT PIECING Rodale's Successful Quilting Library that will help you. Published by Rodale Press, Inc. Emmaus, Pennsylvania.ISBN 0-87596-760-4. Try Amazon.com or BarnesandNoble.com using the ISBN No. and maybe you can find one used.
A variation for clarity from their instructions. When you need to match the short side of a right triangle to the edge of a square or rectangle, you'll notice that the triangle edge is longer than that of the square. For 1/4" seam, align the pieces so the edges match. The tips of the triangle will extend beyond the corners of the square. Pin the two patches together. The triangle should intersect the square exactly 1/4 inch from the side of the square. In other words, the square and the triangle points should meet at the stitching line, leaving the points of the triangle "sticking out" After stitching and pressing the seam to one side, trim off the extending triangle points to reduce bulk in the finished quilt.