Connect with people on LinkedIn that are in the same niche you provide products and/or services to. Form a relationship with them, find out what problems they are having and deliver solutions specific to their needs.
People don't buy from the most intelligent or skilled, they buy from those they trust.
Jef Lippiatt Owner at Startup Chucktown
I would say get out can connect with professionals and business owners within your target industry. Look for ways to have meaning conversations with people and building rapport without trying to sell them something. This lets them know you are looking to make a genuine connection.
Once you have made some connections leverage them. Show them your service or product (again without trying to sell them). Look for genuine feedback and criticism on ways you can improve your offering. If they think you are on to something, ask them to share it with others that may be interested. Even in this digital age, word of mouth marketing or advertising is the most powerful sales vehicle. As mentioned above, people buy from those they trust.
Join several industry groups to stay on the pulse of what is going on within your industry as well as keeping tabs on potential talent and competition.
This may seem far-fetched, but talk to competitors. If you speak with a competitor that is not in your current geographic area and you both are not looking to immediately expand into overlapping territory you'll be surprised at the amount of candid detail they are willing to share.
Lastly, the most important way to drum up business is really simple, but not necessarily easy. Get to know your customers and stay in constant communication with them. Get their feedback and act on it rapidly. Show them they are valued and you'll get plenty of participation. Remember without customers, you have no business.