If you’re like most marketers, you are looking for ways to get more people into your store (whether it’s physical or online). Your job is to grow sales, and one of the best ways to do that is to offer a promotion to customers, new and old.

Below is a brief description of the three of the most popular promotions, or sales, along with a breakdown of why they work.

Promotion #1 = Free Shipping

Customers hate hidden fees. And shipping and handling costs have long been seen in exactly that light. It’s an added cost, usually unknown to the customer until the moment they decided to buy. It feels like they’ve been duped. And a large percentage of online shoppers report abandoning their shopping cart in the middle of the checkout process upon being met with an upcharge for shipping.

So a free shipping promotion feels like a win for customers. Since most companies charge shipping, it sets you apart. If you usually charge for shipping, it presents a limited-time incentive for your customers to come back.

The best uses of a free shipping offer that I’ve seen include a limited-time offer to all customers, a threshold offer (ie. free shipping on offers over a set dollar amount), or a standard free shipping policy (all orders, all the time).

Promotion #2 = Buy One, Get One

BOGO deals are something you are likely very familiar with. They are like regular discounts except that they require a commitment from the customer to take advantage. Instead of offering a discount on all purchases, a BOGO is a discount on secondary purchase. Buy one at full price and we’ll throw in a second for free, or at a discount.

For the reasons mentioned above, BOGO deals are win-wins. The customer wins by getting something they normally would not get (a discount). The company wins by selling more items than they normally would (at least one item in each purchase at full price).

I’ve seen BOGO promotions work as a limited-time incentive as well as a permanent offer. For example, my company, Distance Education Co., offers a standing discount of 25% when enrolling in more than one online course.

Promotion #3 = Free Trial

The free trial offer is one of the best promotions, provided you can make it work. And not every company can.

It works because it lowers the barriers of entry for customers, eliminating one major hurdle, fear. They fear being ripped off. With a free trial, that fear goes away because they can try the product before committing any money.

The key to making a free trial work for your company comes down to two main factors. First, you need a product that wows customers. Second, you need mechanisms that effectively turn “free” customers into “paid” customers. If you have both of those things, you can likely increase your sales with a free trial offer.

Bonus Tip: Make promotions social.

Want more people to take part in your promotions? Incentivize people to talk about them.

You might offer a coupon on your website that people have to claim. When they claim it, you can ask them to share it to Facebook or Twitter, thereby increasing the coupon’s exposure.

You might offer free shipping to anyone who likes your page or tags you in a photo.

Whatever it is, when you incentivize social sharing, you are likely to attract new people to a promotion than you otherwise would. Get creative.