isn't as tough a thing to do as you may think, but you have to have something that separates you from every hardcore gun nut.
I'm a 20 yr gunsmithing veteran but started as a young apprentice in my Grandfather's shop, and it took years until I actually got the idea down. It's not a lot of crazy fabrication any more (like when I first started), the client base can do anything they want to with modules and don't have the same budgets or desires they once did for customs. If I had to start a business today it wouldn't be a gunsmithing general shop, it would be a refinishing and ultra custom shop, and I would spend a year or two working on projects and marketing before I even started to court customers, and then I would work only with heavy hitters with no budget limitations. Ideally we would all do this...but it takes time to get to that point. Become an expert in a specific non economy tied segment of the market, and differentiate yourself from your competitors. Don't ever forget, if you are working on mainstream guns, there is nothing you can do that someone else cant be paid less for and do satisfactorily, so provide excellent service, and bring value to your customers.
If you want to check it out I have some tutorials and basics on gunsmithing on my blog at www.netgunsmith.com
I would also be happy to talk with you via email or chat if you have specific questions.