There are lots of people to interact with in HM64, and having a social life is just as important as having money. Besides the shop keepers, the most important characters are probably the 5 girls that you can go out with. It's probably best to pick one girl early so that you can focus on developing a relationship from the beginning.

The Basics of Dating

Location People
Bakery Elli, the baker, Elli's Grandmother
Flower Shop Popuri, Popuri's Mother, Popuri's Father
Green Ranch Ann, Gray, Ann's Father
Mayor's House Maria, the Mayor, Maria's Mother
Vineyard Karen, Karen's Father, Karen's Mother, Kai