very interesting topic, Prahlad.

Don't sell on credit. There is always a customer out there to pay up-front. Find that one.. and forget those who are using your products and not paying you.

Along with desiging good products, develop the skills to find such customers who are willing to pay. There is no use handing over (not selling) products and then running after the customers.

There is another drawback of offering credit. While using the product for a long time, the customer realizes many features (or his desires) are not present in the product so he blocks payments and asks you to improve the product first and gives you references to other products which have those features (and it is quite possible that by that time the feature rich products are even cheaper than your then selling price).

You refuse to improve and .............