Get a website...that should be your number one. Go EVERYWHERE on the internet and make sure your business is listed with sites like yellowpages.com, merchantcircle, yahoo, google, etc, etc. All these sites will bring people searching to your site.
Do good work. If you do good work, have fair prices, word of mouth will get out. But, word of mouth is very overrated for beginners. Word of mouth isn't going to fill your schedule for the week until you've built a customer base with hundreds of people. In the beginning...word of mouth is not enough. You need to get out there, hand out business cards, flyers, make deals with businesses, dealerships, etc. Once you're doing well enough...you can deal with those accounts then.
BE AT THE SHOP! Do work! Even if it's your own work. Put up some signage, and just be open. Customers will stop in, ask questions, take cards, etc. Just the simple task of being open will help you. Doing work, brings more work. I can't count how many times people stop in while we are working and say "I didn't even know this place was here!" Then BOOM...instant customer.
It might sound stupid...but be professional! Not just professional...very professional. Listen to the customer, and suit their needs. I've gone out in my area personally and stopped in to shops just to see what it's like...I was disgusted, and immediately knew my business would take off just on customer service alone.
In the beginning, you have to fight. Go get some steady work lined up. While you are working on your steady work...things will start to fall in to place a bit for you. There's so much more...but I'm done typing for now, ha. Good luck!!