Here are some Hometalk projects that explain how to do that
The easiest us to paint.
That would depend on what the furniture is made out of.
Is the furniture solid wood, wood veneer, laminate, or plastic?
A picture of the piece would help illustrate what you are starting with.
I refurbish tons of thrifted pieces, here's a link to my projects - https://www.justalittlecreativity.com/category/decorate/furniture
It depends on what you're working with, if it's wood, or something else. Usually I'll make any repairs and then paint.
I usually repaint or decoupage. It really depends on the piece, its condition, and what I want to do for that particular piece of furniture.
Are you hoping you refinish Furniture for profit, or pieces to keep? Here’s a link to some tutorials I have! https://thriftednest.com/category/projects/furniture-makeovers/
There are loads of ways and it depends on what the piece of furniture is made of and how it's finished. I just saw some great ideas on Hometalk -- did you check around using the search bar at the top left?