Obtaining items and achievements is the best way and quickest way to progress in Animal Crossing: New Horizons. There are a variety of challenges and things you do while on your island. Something you can try to do quickly is the get eight items from a rock and collect the rock-splitting champ achievement.
To retrieve items from a rock, you first need to choose to have the tool of an axe or a shovel. It does not matter which you pick or of what quality they are. You probably want to use the axe because you receive it first in the game, and you get the shovel from Blathers later on.
What you need to do is dig holes around yourself for the best results. All rocks are on a timer for you to try and hit it enough times to reach right items. You want to prevent yourself from moving backward because all of the rocks have the capacity to give you eight items. To reach this timer you need to stop yourself from moving backward and missing the correct hit. So, if you trap yourself next to the rock, you can reach the timer and hit everything on time to acquire all eight items from it. You also want to make sure there’s enough room for all of the items to spew out around you. It takes some timing, and luck.
There are plenty of ways to earn Nook Miles in Animal Crossing: New Horizons. Make sure to regularly explore your island, the other islands, and try to reach out to friends to investigate their island if you have the chance.