Skele farm, village farm. Upgrade your gear, you can still get efficiency and unbreaking on your pick, a good sword, bow, fishing rod, etc. Skele farm will get you all the XP you need, and alternatively you can use the village farm to make a bunch of librarians to get more enchantments.

You also should go to the nether and start searching for wither skulls, a blaze spawner, and nether wart so you can start crafting potions. Wither skulls are used to summon a boss that gives a nether star, which you can turn into a beacon to give a huge aura buff around your base.

Alternatively, you can spend more time building your infrastructure, using nether minecart tracks to build some bases in different biomes, and start mapping out the overland.