I always do the painting. I'm kind of a fanatic and paint at other people's homes too. It's fun and theraputic for me.
I prefer the paint at Lowes over Home Depot because it has better coverage but my favorite paint is Benjamin Moore.
Try to get a paint with primer already in it so you won't have to paint it twice. A small room can handle a few choice big pieces. You will also need to think about building up and making certain what ever furniture you choose has legs where you can see under that piece of furniture (no skirts). Skirts on furniture give it a weighted feeling in the room.
I choose my colors based on the colors I like. Neutrals come in many colors and hues. Right now my bedroom is chocolate brown. It gets loads of light. I have had beige rooms, yellow, green, red, pink, various shades of blue, purple, and of course whites. I would say go with some version of your favorite color. It will make you feel good everytime you enter the room. If the room gets loads of light, you can go with a deeper or richer color. We have done ceilings in white, light blue, toffee, and butter colors for various rooms but these themes would work well in any room.
Other ladies have given your some great suggestions on supplies and especially the drop clothe thing. Most rooms take about 1 gallon of paint. Your roller doesn't need to be dripping with paint before it hits the walls but should have been loaded with paint so it is covered but not dripping. Applying the paint in a huge W pattern to start on the wall and then filling in the missing areas works best. Make certain you tape off everything that needs tape first, then paint, the remove the tape while the paint is still wet.
Have fun with it. I'll be doing some painting in the next few weeks. I believe I'm going to do some shade of yellow because this space is kind of dark and needs some brightening up.