The game opens up a lot once Nook's Cranny is established, so follow your star! If you want to design, explore for more DIY recipes.
If you want to get a bigger house, collect fish and bugs for Bells, and maybe participate in the Stalk Market. If you want to keep building your town, make sure you set up your new resident's houses quickly when prompted to. Iron Ore can be tough to find early on, but visiting deserted islands and hitting rocks there can yield plenty. This is key for unlocking more town features. When prompted, invite them to come to your island and live. You get this by donating fish and bugs to Tom Nook until Blathers shows up and then to Blathers until he builds a Museum. This gives you a place to catalog unique bugs, fish, and fossils, as well as unlocks the Vaulting Pole and several other things. It gets you out of your tiny tent, and lots of other elements of the game are unlocked once you're in a proper house. You can do this very, very easily by selling fish, bugs, and shells.
