Hello! There are a few guides online but it really just boils down to some basic tips that I'll list here
- Speak to your villagers each day.
- When you can, send letters. Letters with perfect grammar and a gift such as perfect fruit yield more points and a better response.
- Finish the various errands that villagers frequently request. You get more friendship points if you give perfect fruit when they ask for fruit, a highly-valuable bug / beetle when they ask for an insect, or a refurbished item if asking for furniture.
- Compliment them at the end of house visits.
- Agree with them during multi-villager conversations.
These are some super simple things that I can remember off the top-of-my-head!