When I first started out, I got in touch with my local FMB (Federation of Master Builders) - The Chairman was a very helpful chap and send me via E-mail a list of all 173 members in the Dorset area - Once armed with this info, I proceeded to do a letter to every member telling them who I was , what I did and offered to show them the quality of my work if they ever needed a plasterer - Got several good contacts from this approach, ones that still use me today
And like Spoon85 you cant beat a bit of free advertising outside the builders merchants or DIY store - Get some 'company' polo shirts (more professional than t-shirts) printed up and make sure you wear them whenever you go to busy places - shopping, the match, PC World , anywhere - You'd be surprised how many people look at logos on shirts cos they are nosy and one of them might just need a spread