Web companies need to stay on top of the constantly evolving methods of advertising on the web. Trends regularly emerge in this sector, so it can be difficult to keep up with what is important to know in the world of digital marketing. Here are six current strategies that are proving to be effective for increasing online sales.

1) Retargeting.
Shopping cart abandonment is one of the biggest concerns for an ecommerce business. Consumers find your site and view product pages, but leave without purchasing. Even optimally designed ecommerce sites suffer from what can be called "delayed buying" or customer indecision. Industry research has revealed shopping cart abandonment rates are at 80 percent and greater, and the top reason for abandonment is simply that the shopper was not ready to purchase at that moment.

Enter an advertising tactic called retargeting, also known as "behavioral remarketing." Retargeting tags shoppers who abandon their shopping cart, and follows them around the web, serving them ads for products they have shown an interest in on your site. For example, anyone who has recently abandoned a shopping cart at Zappos.com has been retargeted when visiting third-party publisher sites later on. Zappos serves up an image of the specific shoes you showed purchasing interest in, along with the brand and product names. Sierra Trading Post, Macy's, Ace Hardware, Dick's Sporting Goods and other major ecommerce brands have invested heavily in this marketing tactic. Ecommerce powerhouse GSI Commerce thought enough of retargeting's potential that two years ago it purchased Fetchback, one of the leading service providers in this niche.

Case studies from Fetchback and online marketing service companies like Criterio, Media Forge and Sweet Spot Marketing show that retargeting is one of the most cost-effective ways to capture lost leads while lifting sales. Retargeted ads cost a little more than regular banner buys, and should not be considered a marketing savior. Rather, the tactic is best integrated into a larger ecommerce advertising plan involving search, affiliate marketing, email, and social media. Studies have shown that the combination of retargeted banners with paid search can be effective in increasing the likelihood to click through both organic and paid search results, while lifting the willingness to buy on a site.

2) Abandoned shopping carts email.
Companies like RedEye, SeeWhy, iContact, ExactTarget, Responsys, and others offer trigger-based programs that let e-tail brands send emails to consumers who abandoned shopping carts. The consumer must be logged into the site, as a past customer or registered user, for the program to take flight. Cataloger Clifford James recently authorized a case study that stated RedEye's program helped lift sales dramatically. "This abandoned shopping cart behavioral email campaign achieved great success within the first three months," says Brian McConnell, a commercial director at RedEye. "Significant improvements in deliverability, click-through and order rates contributed to a 154 percent revenue increase, with a 678 percent ROI."

3) Facebook marketing.
Some say the future of digital advertising lies in social media. Starbucks, Levi's, Nike, Heineken, and Domino's Pizza are a handful of names putting their money where their mouths are, launching global Facebook ad campaigns during the last 18 months. But SMBs should not be intimidated from putting this platform to use. They can buy Facebook Marketplace ads, the sponsored slots on the right hand side of a user's page, with minimum bids of $0.01 for cost-per-click (CPC) or $0.02 for cost-per-thousand impressions (CPM). Campaigns can be capped at low dollar amounts like $25 per day, enabling e-tailers to test ad strategies without breaking the bank. The ads can be geo-targeted to precise user interests. For instance, if a sneakers store owner in Texas wants to only target Dallas-area residents who have "liked" Nike on the social site, interest-level and area code parameters can be set on the self-service platform at www.facebook.com/ads.

What has made Facebook advertising attractive to brands is that it increases their fans on the social site. After consumers become a fan of a company, they will see posts from the brand in what has become known as earned media marketing. Once a marketer gains Facebook fans, messaging to them is free. All the brand has to do is set up an official Facebook Timeline page, which became available to all companies at the end of March. If you have short product videos, Facebook is an excellent place to repurpose the efforts. They could go viral.

4) Twitter ads.
Every user of this micro-blogging site has said something close to the following at least once: "I first thought Twitter was stupid. Then I tried it, and it's a great place to catch up on the news of the day." Thus, if you are a business that has yet to establish a Twitter account, perhaps the time is now, because the platform is becoming a great place for marketers to promote specials and new products.

As is the case with Facebook, branded Twitter pages are free to set up. Then, the company just needs to pick up as many followers as possible. For free, the marketer can start following Twitter users with hopes that they follow back. While that is one way to get the ball rolling, brands can also test Twitter's ad units, Promoted Accounts and Promoted Tweets. Marketers bid on keywords, akin to Google AdWords, and the ads start appearing when users either perform a Twitter.com search or in their news feeds. Promoted Accounts, in particular, are designed to grow a company's audience on the site. American Express card members have recently been pitched with $100 worth of free Twitter ads for the first 10,000 SMBs that sign up. (At press time, there were still open slots available for the freebie ads at ads.twitter.com/amex.) In the last several months, Twitter pages have been enhanced to enable product videos and other multimedia marketing capabilities. Additional information on Twitter marketing opportunities can be found via business.twitter.com.

5) Free classifieds.
Submit your site to directories like Yahoo! Classifieds, where businesses can post about products and services at no charge. This tactic works particularly well for getting sweepstakes to go viral on the cheap.

6) Advertise URL on everything.
Whether it is a direct mail piece, a Yellow page ad, business card, an email campaign, or the signage in front of the building, always promote the website. The free impressions your company's properties can create should not be underestimated.