Studio Furniture and Easels
If you're getting serious about painting and have room to set up a semi-permanent studio, these are the things I recommend for dealing with small spaces, on a budget. If you paint often and for long periods of time, you'll need to have good posture in your studio to prevent stress injuries. I don't have any training in ergonomics, but I paint every day and I had to make some adjustments to my painting habits to prevent muscle strain. This is what worked for me:
A French Easel
These folding wooden easels were originally designed for plein air painting (painting outdoors) but are ideal for putting in a corner of a room in a semi-permanent location. The design of french easels has remained virtually unchanged for the last several hundred years. I think they're a good compromise between a travel easel and a full-size easel; they're portable, yet sturdy, and you can get one new for as little as $80. Unlike ultralight travel easels, french easels are pretty stable, but fold up to the size of a breifcase, weigh only 13 pounds and are quite adjustable to your height and painting preferences. They have a little drawer which is handy for holding paints and brushes. You can also remove the legs and put the easel box on a table.
An Adjustable Lamp
There are plenty of easel lights avaliable, but they start at $100 and up, and I've never found one that I like. I use a plain old swing-arm clip lamp, which was about $13 and it works fine. You can adjust your light temperature by trying different types of bulbs - the energy saver ones work well and cost under $10. Many artists would argue that you need to replicate daylight with your easel light, but I think it's more realistic to replicate the type of light your painting will be displayed in, which is probably similar to what you have in that room already. I think it's more important to get up from your easel often and check your painting under different lights, even hang it on the wall. Do get a light that's bright enough to avoid eyestrain, and can be adjusted to comfortable working heights, so you're not hunched over.
A Supply Shelf
Like with everything else, you can buy a special "for artists" model of a wheeled shelf, called a taboret, but you can usually improvise for a quarter the price. Spend your money on good paint instead. I use a kitchen cart, but I've heard other artists also use old baby changing tables or filing cabinets with wheels. The idea is to have something you can park within reach of your easel, with a flat surface to hold your water bucket and brushes, and storage below for your paint tubes, rags, etc.
I recommend covering the top of your shelf and the other surfaces in your studio with clear plastic, so you don't have to worry about marring wood surfaces with water or paint. I love the clear plastic "shelf paper" (which is not paper at all, but is still called shelf paper) that you can buy at the hardware store. It attaches firmly to most surfaces but also removes easily, especially important if you're renting.
A Good Chair
This is an area where people tend to have very different preferences. Old-school artists say it's best to paint while standing, so that you will step back often and look at your painting. While I definitely encourage this, it's easier said than done. If you prefer to sit, you have to be very careful about the chair you choose, and how to place your supplies so you're not reaching, squinting or craning your neck. When I started painting full-time, I switched to a kneeling chair, and I haven't had any back or shoulder pain since. Some people prefer a high drafting stool. Go to a store and sit in the chairs for a long time to try them out. Make painting motions and hold your arms at painting height to see if your shoulders get sore (people will look at you funny, but who cares?). Better yet, borrow a stool or kneeling chair from a friend for a few days and try it out. If you do stand and plan to paint for a few hours at a time, wear some comfortable shoes with arch support so your feet don't get sore.
Apron
When I started out as a painter, I painted only in watercolor, which generally comes out of your clothes, and I got in the habit of wiping my brush on my jeans when I wanted to use a dry brush technique. This was fine until I switched to acrylic, which doesn't come out of your clothes. I get very involved when I paint and I went through a few pairs of nice pants before I decided to just wear an apron. I purchase heavy denim potter's aprons, which go down past my knees, and they work nicely for covering my clothes without getting in the way of my arms. You can also use an old men's shirt, worn backwards, but it doesn't protect your pants.
Gloves
Acrylic and watercolor paints are very safe, so I don't use gloves when I'm working. Gloves are recommended for oil painting. To make it easier to wash paint off my hands and arms after a painting session, I use a product called Invisible Glove before I start, which is like a thick hand lotion that coats your skin and forms a barrier. I think that a regular thick hand lotion would do the trick as well, as long as it didn't make your hands greasy.