First decide how wide you want to make your weaving. On a weaving loom you can never create a wider piece than the width of your loom, but if you want to make a smaller piece on a big loom, you can warp only part of your loom.
Second. Decide how fine you want your final piece to be. This depends a bit on the fibers you will use for the weft of your weaving project. You can choose to place one warp thread in between each notch or place the warp thread twice or four times in each notch. Your weaving project will get stronger and allows more details when you warp two threads in each notch instead of one. If you want to make a very detailed piece, and work with fine fibers, you could go for four threads in one notch.
In the below example we will show how to warp your loom with two warp threads in one notch.