for 8.5 x 11 inch size decals, printed on an inkjet ---- I would try something like papilio paper. but understand that these would not be as strong or permanent as other methods.
next, if you want to contour cut them - your software for the cutter would also have to read crop marks, -- its a learning process in itself.
for wide format - you have latex, and eco-solvent and others- you can do a search on those terms for threads.