Starting IT Consulting company

I am going to be starting a small IT Consulting company. The first day of business will be Oct 1. I am taking on work after hours and on weekends right now with some existing clients I have built up (3 total). I want to focus on small business around 1-10 people in a specific industry. I was hoping I could get some advice on how to get lists of these types of companies in my area? For now I have been going into office buildings and just walking in and introducing myself with a small short pitch and giving them my card. I will continue this but would like to try and do a little more focused campaign. Any advice and direction would be greatly appreciated. Thanks you in advance.