I use to cut my fabric into triangles before sewing but stopped doing that after I watched Eleanor Burns. It is so much easier to draw a line on a square and sew a 1/4 of an inch on each side the cut them in half. But if I have to make a multiple number of hst I will place 2 fabrics right sides together, figure my measurements, example: for 4 1/2 in hst, to get 16 hst, cut fabric at 10 x 20 inches, mark fabric 5 inches all the way across the 20 inch side, then down the center of the 10 inch side. Then draw a line diagonally every other square set, the repeat going the other direction. Start sewing 1/4 inch on each side of all diagonally lines. Then cut apart on all drawn lines. Very easy. I hope this makes sense to you, if not here is Eleanors site for how she does this method making a bear paw block.
http://vimeo.com/album/1321436/video/15469320