Not An Easy Answer
What do you know how to do, and what do you want to learn?
When I wanted learn to dovetail, I made some dovetail boxes. I made a couple to hold tea bags. You can have fun with the wood. My favorite one was made out of maple and cherry, I gave it to my sister.
Small end tables are fun and will help you learn mortise and tendon joinery.
A foot stool can come in handy.
Start with something you know, and try and learn something with each project. The more you try the better you will get.