One of my friend created a Desktop software for small business.He was giving free trial license and download for 30 days. Adwords gave him 50 daily propsects.It took him 6 months to get his first customer and 2 years to reach 200 total sales. But in the process he learnt a lot about that specific industry ,added lot of features to his product and also added an online offering. Now he is selling 60 a month.