A l i a s A u r o r a
This didn't help at all. The codes are all messed up, and half the links don't work. And I don't have Photoshop.
Still makes perfect sense to me. What did you need answered, specifically?
To the earlier person wanting to start a shop, my biggest piece of advice to a new shopowner is this: Make some pets first. Make at least ten pets. Make them of a really good quality. And make yourself make them to a time limit, like say, a month. If you find this process tedious, you will know that you don't have the time or energy to run a shop.
There is definitely a market for pencilled pets, I think; some of my favourite artists make divine pencil works. But pencil is a difficult medium to get right.
No matter what medium you choose, any pet maker needs access to two things: a program for manipulating art (many are available for free online - see the link posted further upthread), and a method of getting your art into the computer (a scanner, or a graphics tablet if you plan on making your art directly on the computer). If you have a program but no scanner/tablet, you will be forced to make art with the mouse, which is beyond the skills of most. If you have a scanner but no program, your scanned drawings will be obviously 'scanned' and will lack that clean professional look that people like. You really need both, or a looooot of time to learn to draw well with a mouse.
To answer the ever-present question of 'how to make pets grow' - which, like everything else, is answered on the first page - You draw the next stage of the pet, and upload that into the same place as you did the original pet.
For example, say I make an egg and call it 'dinky.jpg' when I upload it. The url will be
http://thisisanexample/dinky.jpg or whatever. When I want the egg to 'hatch', I upload the new picture (it's a dinosaur, sweet!) with the same filename, which will overwrite the original egg image. Now wherever anyone has the image linked (say in their sig) it will now appear as a dinosaur. Cool huh?
Of course you don't need to do it that way. For my shop I just make a new URL each time and post the new URL in the shop, because my imagehosting doesn't allow you to choose your urls. No one seems to mind, and there are some benefits to me for doing it that way, but the 'usual' way of doing it is as I've just explained.