Some things that worked for me were;
-writing and sending mail to villagers
-watering flowers
-selling any trash items you fish out
-completing favors
-pulling weeds
-putting messages on the bulletin board
-selling furniture in the retail in the area where villagers buy it instead of Reese
-talking to villagers
It always takes a couple days for me so I usually end up time traveling for it. I hope this helps!