Business cards and personal networking - get yourself known.
+1. Advertising is expensive and not always effective. Don't assume, for instance, that even a top-notch website will generate any business, because Google will throw up dozens or even hundreds of other similar sites for pretty much any business you care to name.
You are looking for work which is at least within driving distance, and shop-fitting is a trade where almost everyone who needs it already has established contacts, so as Accountantpete says, the best way is to get yourself out and about within your trading area. By all means have a website, but more as something to point people to than expecting it to pour enquiries into your Inbox.
Then it's just the usual - target peer leaders and do a professional job to generate referrals.
+1 to that as well. When I started my first business from scratch, we - solicitors - were not allowed to advertise. Even when we could 10 years later, we never did apart from very occasional sponsorship. Certainly where you are doing something for your customer, rather than selling them a finished product, it is cheaper and easier to get your customers to advertise for you by doing a good job - and IMO better for your soul as well.
One practical thing that we did was give people a 'How did we do?' form a week or so after the job. First, they appreciate being asked; and second, we got a lot of useful feedback from the occasional "You were crap because ..."