I'd say to go to the local library and check out a book about selling your crafts. There are many of them on the market now so you should be able to find one that fits your style.
I think that if you want to make your hobby pay for itself, start small and use the proceeds from that to re-stock your needed supplies for the next project.
Some of the problem overhead is to have to pay for space at a fair or a booth at a local school craft fair. If you can use your home as a store front and have a craft show at home that would save you the cost of that. Or sometimes selling one item leads to extra sales if that person is willing to give your name out as the maker. Take advantage of the market buy and sell boards too, it is amazing how many people look at it in a day.
But, you have to look at your market in your area and choose something that will sell first. Purses are a good choice, or maybe tote bags since they are stopping them in the stores. You have to be able to buy low and sell high. So, to begin with check out the discounted fabric stores (or supplies, like d-rings for instance) You have to have something that everyone else doesn't have, so try and think of something you would like to have that everyone else isn't selling. Think Girl! What would you like to buy at a craft fair?
I think maybe the way to start is to put it down on paper and start from there. You can see things down the road better if you have a plan.
Red