A huge mistake I see by people trying out their e commerce shops is to offer discounts. They offer coupons, probably because shopping carts today have very easy ways of integrating coupons into their checkout systems. And people think that by offering coupons they'll attract more customers. And all of these reasons are probably partially true.
But the biggest mistake I see is that the coupons are crap. When you're offering something online, and you're not known, you've got no brand, you have to believe in what you're doing. So much so that you should almost give away your first product for free. After All, wouldn't you give away your first product if you knew that the customer will come back for more products after? That should be your mentality.
Give away a taste, a freebie then sell more products to that customer. Find out more about them, learn why they wanted your product, how can you make it better? The first product is often called a loss-leader. So why not go balls out and give a 50% off coupon? or a $60 off from your first $100.00 purchase? Now those would be coupons that get my attention! And I'd be happy to Tweet, Facebook, share and Google+ the crap out of that offer, bringing you more clients.
I'd even send an email out to my friends or family members that might be interested in that offer. And guess what? You have now attracted the attention of buyers willing to spend some money to get your product.
I believe another reason that people do the crappy 5% or 10% coupons is because they're too lazy to figure out how to market to them again. Here's the secret sauce to that... email marketing. Before you give away a product or offer a 50% discount like I am suggesting, make sure you have a sytem in place to help you promote more products or services to that customer. Get them to share their email address with you and then use it!
-- Believe me, this is cheaper than any advertising campaign you can concoct. Do it. Next time skip the bullshit 10% off coupons. Give them something to chew on, something substantial. And milk it. Ask them questions, ask them to share the amazing offer in social networks, and follow up with them by offering other products that will also benefit them. That's how you do business online and how you acquire new customers.