Probably no "easy" way exists. Still, if you take the project stage by stage, you can estimate pretty well. Looked at individually, the wings, fuselage and tail are separate projects and a list can made more easily for each. If you are starting with one of these, let's say the wings, make sure you have what you need specifically for that job. Running out of sticks or sheeting is annoying but what holds you up is running out of key wood supply for the item you are working on now. It helps to be familiar with the common sizes that wood comes in, especially that which is available locally as opposed to mail order stuff.
I have made sketches of sheeting, say 8 sheets of 1/16"x3"x36" balsa - then sketched onto it the parts that need to be made from it. This works very well if you are designing something in CAD where you can make a materials file, then copy the parts and 'paste' them directly on the sheeting - to figure the most efficient use.
It does help to have a supply of wood from previous projects to fall back on so if you over order, the wood is still good for the next project. Most of the wood blocks and heavier AC ply that I have used came from the 'supply' box.