Writing device drivers

Hi all, I've followed up LDD3 and started off with writing device drivers . As usual i've started with char drivers given in that book and also started to make minor modifications to learn it better and so on. Now i would like to know how to take it forward and start writing drivers for a profession. I know its too early to call myself a guy writing device drivers but how do i take if forward from here so that i can become one. Is the only solution to pick up a device which does not work on linux and get it working? Are there any other ways as well? Shampavman