The most important thing is to figure out what range of pricing fits your area. You don't want to sell yourself short but you also don't want to price yourself out of the market. What might be a perfectly acceptable price in one area might be way high or way low somewhere else, so I'm not going to try to tell you specifics.
I will say that you want a variety of price points to fit various people's budgets. You need a good quantity of under $20 items, possibly some under $10. Your next price point will be $30 - $40 items, of which you should also have a fair quantity. The $50 and up items are what will start to pay for your time and effort, but in my area these might not move as fast as the lower priced items. In other places they may fly off the table.
Pricing by size is probably the easiest, but you may also want to consider complexity as well, especially on your larger pieces, even though we all know smaller may actually be more difficult!
Good luck on your venture.