When it comes to needing multiple Half Square Triangles here is a quick way to make multiple HST at one time.
Here is also a copy of the cheat sheet if you want to keep it handy for the sizing charts. Four-at-a-Time-HST
Once you have two squares cut based on the size needed from the chart, draw two diagonal lines to form an "X" across the middle. Then the two squares together by sewing a 1/4" around the outside edge of all four sides of the two cut squares. Once finished sewing, cut using the "X" guide lines, unfold each HST, trim, and square. You now have 4 of the same HST based on the size needed.