One method I use to make 1/2 square triangles is to cut two squares large enough to make 4 sets of two 1/2 square triangles, put them face to face, and sew 1/4 inch seam around all 4 sides of the square. Then I very carefully cut an "X" through the center of the square. That produces 4 sets of already sewn together half square triangles.
Practice a few sets using this method with scraps to ensure you have the 1/4" seams are right and that your "X" is centered. As with all things quilting, precision is important.
I also have an accuquilt that I use to make 1/2 square triangles. It was purchased because cutting has become difficult for me. It's like a miracle. both for accuracy and for my arms and hands.