Blueberries are the best possible thing in summer, cranberries in fall, buy all that shit and farm the shit out of it. Make sure to contribute to community center bundles whenever you can, prioritizing the ones that repair minecarts for fast travel and repair the bus to go to another location with the best seeds in the game for Summer Year 2. A stable also helps once you can get hardwood because a horse is so much faster. Don't bother with basic sprinklers but once you can afford to and learn how to make some quality ones. Artisanal goods such as jelly or wine cost a multiplier of the basic fruit/vegetable you put in, so put the most expensive ones per unit you have in there that aren't gold or silver star for maximum profit.