I was taught that you measure your draw length from the groove in the nock where the string fits to the deepest part of the grip plus add 1 3/4" to that. Your arrows need to be spined right for your bow, draw weight, draw length, and length of arrow. But we need more information about the bow (like amo ,weight and draw length)to help get the arrow close to the range in spine you need. If I'm missing something or didn't explain it right some one else may able to explain it better. What bow are interested in buying?