I think you should start with a few freebies first in order to see what you would like to do. Texturing clothing or characters is always a good starting point and there are tutorials available on the matter, because no matter which path you will chose later, being a good texturing artist can be the key to success. Allow a year of releasing freebies and see how the market responds for it isn't as easy as it used to be and it will take loads of work for very little pay. See it as a hobby with a possibility to maybe earn some cash later on. You don't need to buy the very pricey software first as it is all a question of skills. I have seen people knocking out killer textures using PSP. Photoshop is of course the better software but think about this wisely. Don't invest into modelling software as of yet for they can cost loads. When ready try the free or cheaper ones to understand the concepts for versatility in many different softwares is great. I have done all of it, texturing for free and for sale and I model simple stuff but it didn't happen overnight. Feel free to ask questions of course....