I listed them in order of prioritization and importance.
1. Hints / Tutorials / Tips. (Not to many, as finding things out on your own is half the fun.)
-How to find Ylands. So someone doesn't sail in open ocean for hours wondering if they are unlucky or just sailing into nothingness.
-Key crafting Items tab needs to be pointed out.
2.Crafting Menu. Adding a tab for most recently gained recipes would be extremely helpful.
3.More Clay deposits.
4. Ships. Add a Cargo hold to the large ship. Add a life raft or boat that you can craft and place on the ship. So you can sail to shore.
5. Add a rope that you can climb up or down.
6. Abandoned towns with loot and such.
7. Boss monsters in caves. I haven't fully explored a cave yet, so not sure if there is any, but if not there should be.