A extremely short guide to assist with a resource that seems extremely chance based.
Enshrouded Obtaining Resin
So Resin seems annoyingly awful to try to obtain but it also looks to be a resource that you will need plenty of in the future. As far as I can tell, resin has a chance to drop from any tree your chop down but one tree in particular looks to have close to a 100% to drop it every time. You should be on the lookout for any trees that have orange/yellow leaves. This should save you from pulling your hair just looking for drops. Good luck.