First, you need to decide if you are going to build a reflex, flat or string follow design. It should be 1.5" wide and a full 72" long. It does not "need" to be 72" but it will be more versatile if it is.
You can build fire hose style or rubber band style or clamp style. They all work. Just depends on what will be best for you. Rubber bands and clamps allow for more versatility in design.
DO you want to build a true Hill style bow, or an ASL that doesn't necessarily follow Hill spec's?
If you want an ASL without following Hill spec's, I recommend going with the Bingham design and plans. It will give you a quality bow and allow you to build to a predictable draw weight.
Good luck with It. I know my answers are not as specific as you may like, but if you further refine your question, more help will be practical.