Advice to Get Going in Forge?

I’ve been interested in working on a remake map for Halo 5 using the new forge. I think I’ve narrowed it down to an overlooked map from Reach called Highlands. So does anyone have any tips or advice on how to lay the framework? I’m mostly talking about getting the scale of the terrain right. I think I’ve heard of some methods where people measure the distances using crates side-by-side, but is there any other well-tested and proven way to make a map true to the original?