Anyone who is into t-shirt printing (using heat transfer papers)?

I have painted t-shirts but never tried printing with paper, I don't think it is available in our city.

I tried the printed T-shirt business once and made some money with it. Heat transfer papers is not really the best approach. It's rather expensive, and it does not yield a very high quality product. Take a look at silk screen printing. You can find quite a bit of information about it by goggling it. It's a lot of fun and you can produce a very good product that way. It does not cost a lot of money to get started with it. Good luck in your new venture. Let us know how it turns out.