It sounds like you are starting or wanting to start a consulting business, which is OK. Starting as a consulting business is a great way to bootstrap a company and a great way to bring in some cash. The only problem is that it is very time consuming. Once you start having clients, you'll probably spent most of your time in projects and not able to work on anything else...
Since you have a FT job, you should consider working on the product idea you might have (software) in your free time, instead of consulting. It will help you develop your product faster, and keep you focused on your product instead of a consulting business.
If what you want to do is to start with a consulting business, then consider offering your service to the company you are working for right now, also, look at other local IT shops that you could help with your testing/QA skills, put a basic website with some contact information, look for gigs on craigslist, and other websites for freelance testing/QA opportunities, etc... also, don't forget word of mouth, make sure you leave a good impression on your clients so they recommend your work to others, it is the best way to market any business.