I like to use arcs from a circle. Make some based on about a 28" circle radius for a bow of about 56 - 58" (Really short LONGbow). Draw some parallel lines maybe one inch apart on paper, 60" long,mark your length ends, then using the arcs, draw a bow, the limbs arc one way the riser the other way connecting the limbs. Divide the bow length (on paper) into three (EQUAL) parts, 2 limbs and the riser, and use these dimensions to lay out your bow. You can design in as much or as little reflex and deflex as you need or want, keep everything nice and pretty and experiment.
Good place to start Good luck
ChuckC