I'd love doing volunteer work like that. I have painted a couple of walls for friends, but I've never really put it out there for the public. I might consider it after I get out of here! A friend was expecting her first grandchild, so I painted Winnie the Pooh's woods on 2 walls and part of the ceiling as a baby gift. Turned out great. I've, also, left behind some painted cupboard doors and a small wall or two at previous rentals. I've thought about a painting business, but I really don't know how to go about it.

I can give you suggestions, because i looked into it for myself a while ago.
Begin by building a portfolio binder! You do not have to do walls for your portfolio, artwork and plans for walls will do. You will need about 20 items for your portfolio. They don't have to be perfect, because as you make better you can replace the weakest in the collection, so start with anything you already have and gather it together in a binder. If you do not have enough or want better items, this is what you can start to do before you move. Perhaps make two designs, in color, every week. If you can, go over to the Winnie the Pooh wall and other walls you have done and take good photographs of them before leaving, so that can also go in your portfolio. People need to know what your work looks like before they will contract with you, so a portfolio is indespensible.
Art centers and art schools often offer free portfolio critiques so that you can get professional advice for improving your portfolio. Ask them! Many established artists and art professors are also willing to do it if you just ask. It helps to get feedback, but don't take everything to heart. Just listen to what you find useful suggestions.
These days many artists also do a portfolio online by scanning photos to a webpage or website, and this is very handy for customers to access. You could probably use a place like MySpace or Etsy. If you don't have the equipment to do this, ask around. Public Libraries have computer access for free and may have scanners, also. You may be able to borrow a digital camera from a friend, and these days they can be purchased for under $100. Once you have an online portfolio, the web address should be put on your business cards.
I have learned you can get color business cards for FREE. There is a company that will give you 250 if you allow them to advertise their services on your card. You can also buy cards cheaply through them without their advertising. Get business cards as soon as you move.
Before moving, estimate how much time it takes you to paint various square footage... for instance, a 5 x 4 foot space, a 10 by 8 foot space, etc. Always pad your time UP because there are all sorts of unthought of time requirements, like seeking work, phone calls, going to the store for supplies, waiting for someone to arrive to let you in, etc. Pay yourself well... you can always negotiate a lower fee, and then your customer will feel they negotiated well and are getting a bargain. So for example, you may estimate it will take you four hours just to set up a job and figure it out and get supplies, minimum, and 3 hours to sketch and paint a 5x4 space. That's 7 hours and say you decide to pay yourself $15 an hour to start ($20 might be better... remember, you are not likely to be painting 40 hours a week)... that's $105 to do the job, plus the cost of supplies and equipment (which you can also figure out now for different wall footage). If $105 is too much for them, then you can negotiate lower when you need the work. See?
Also once you move, you can start visiting businesses with your portfolio under your arm by going door to door. Explain you are new to the area and are beginning your business of mural painting (or mural painting and faux finishing!). Show them your work and ask them if they would like an inexpensive mural. You might suggest a wall and something in particular so that they can start to see it in their mind. Plan how many hours a week you will seek business. If you do not have at least one paying job a week, start offering to non-profits that you will do one for the cost of supplies, if they would like, and try to get one of those a week. Ask that you can leave your business cards near the mural with a small flyer explaining your services, for say... 2 months after the project is finished, and ask them if they will be so kind as to refer you.
Tell everyone what work you do. You never know who will want a mural, or know of someone who does. I think if you do this you will find you are soon swimming in work.
Keep a log of every activity you do for your business starting now, from portfolio making to estimating fees, to reading about painting murals, to the actual jobs and what you learn along the way, everything! This will help you get better and better at pricing, finding work, and negotiation. You might wish to plan a certain number of hours a week to devote to this, even before you move. You can be practicing, reading, planning prices, photographing what you have done, now.
I am SO excited for you. I wish we could do this together. I
am looking for a house mate, should you decide to come this way.

hahaha.