The most difficult part to filling out the tree and getting these stars is to, well, grind out the materials. The meats being the hardest to grind out because of the low drop rates.
So I have been slowly working on a guide. The areas highlighted are the highest drop rates I have personally found (and with a little research via Jabbithole to confirm suspicions). It is by no means complete, but I feel okay posting the first two for now. This is spurred by a conversation with DasMoose and Alyred.
I hope this is useful to some folks, and look for the rest of them to slowly trickle over. (You will need to click on the image to see the original size. These itty-bitty thumbnails don't give them justice.)