Going to repeat some of above:
1- go for the blue tape, seriously
2- don’t cheap out on paint. it doesn’t really matter what brand you buy, but make sure you get one that is meant to be a one-coat paint. I just did a room in Sherwin Williams Durability paint and it was fantastic
3- Decide on what sheen you want. Usually there is matte, satin/eggshell, and semi-glass. You probably want the satin/eggshell. Flat paint has absolutely no lustre and it can be really hard to wash. Semi-glass is pretty shiny… probably best used for a bathroom or trim.
4- Get yourself a purdy angle brush. It might cost $20 but if you take care of it, clean it out immediately and well, it will last you 10 years.
5- Buy pan liners so you don’t have to wash the pan. They’re like $1.
6- Take the time to tape really well, it will save you time later in edging and cleanup
7- Take your time edging. Seriously… taping/edging will take more time than painting the whole rest of the wall with your roller. That is the way it should be.
8- You probably know this… but take off your outlet covers before painting. It is so not worth it to edge around them. Just pop out the screws and put all the screws/plates in a bag and then you can paint much easier.
9- make sure you stir the paint before pouring it, unless you literally JUST bought it that day. paint settles sometimes and its such a hassle.
10- when you’re rolling the paint, don’t get so much on the roller that it drips on the wall, and paint in a V shape, not up and down.
Thats all I can think of for now 🙂