Find a good and interesting place to settle, build a giant castle or a cool home on the mountains, build a farm and a watch tower, make your self a little one man settlement/base, explore the world, make a mob grinder, defeat the enderdragon, go to the nether, make outpost scattered across the land and build subways underground to get from location to location, install mods, dig out massive mines and quarries, find a village and turn it into a kingdom, build a horse ranch.
But whatever you do try to stick with the same world