Pricing depends on your experience, costs, and the difficulty or location of the project. For ecommerce photos, you can charge per every photo the client uses, starting at $20 per photo and working your way up to $50. For larger projects that include several products or a whole catalog, you can charge per product shoot.
To figure out what you should charge per shoot, check the rates of more established photographers in your area to get a sense of the market. Then share your portfolio with businesses in your area and offer competitive pricing. As you gain experience in commercial photography, you can begin charging a flat rate. You might go from charging a few hundred dollars for a daylong photoshoot to charging as much as a few thousand.
No matter where you start, remember that with each assignment you learn more and add to your portfolio. Every new problem you solve gives you one more tool in your kit. As long as you keep taking photos, you’ll keep getting better, and as you get better, you can seek more challenging assignments and charge more for your work.