By Elizabeth Loethen

Product placement used to be a secret marketing art, subliminally advertising to television and movie audiences. It’s withstood the test of time because, whether it’s E.T. eating Reese’s Pieces, or Tom Cruise rocking Ray-Bans, it’s been shown to improve sales.

However, it’s important to note that not every instance of product placement is equally effective. Here are a few do’s and don’ts for successful product placement:

Do: have the character use the product to make an impression

People like to relate to a character. Whenever that character actually uses a product, the placement often becomes more effective. After Tom Cruise wore Ray-Bans in the movie, “Risky Business,” the brand’s sunglasses sales increased by 50 percent.

Do: make the product the character

“Transformers” did an excellent job bringing this tactic to the silver screen. My favorite character was Bumblebee, portrayed by a yellow Chevy Camaro. After seeing the movie, I really wanted

a yellow Camaro, just to say that I have my own Bumblebee. As it turned out, I happened to be one of many viewers who had the same thought. After the film’s release, Chevy realized the high demand for this fictional car and released a special edition of the Camaro with the release of “Transformers: Revenge of the Fallen,” which resulted in a 10 percent increase in sales.

Don’t: show too many products

If you saw “Jurassic World,” chances are you caught at least a few product placements. A staggering 35 brands are mentioned or shown in the film, and the constant advertising has

viewers upset. The “Washington Post” called it “a cringe-worthy fact of life for the theater-going crowd.” This is not how you want your movie (or your brand) to be remembered.

Don’t: use fake products without thought

“The Hangover: Part II” contains a good example of why it’s necessary to be cautious when using fake, knock-off or alternative brands and products. Alan, who is played by Zach Galifianakis, uses a Louis Vuitton bag throughout the

film. In one scene, he warns another character not to touch his bag, saying “Careful, that is… that is a Louis Vuitton.” He pronounces the name incorrectly, showing comic ignorance and the fact that the bag may not be genuine. The company was not too happy about this scene and filed a complaint against the movie for trademark dilution since the bag was seemingly fake.

Product placement can be a great tool, but only if it’s used effectively. As is often the case, quality seems more important than quantity.

Have you seen any notable product placement, good or bad? Let us know in the comments below, and don’t forget to follow us on Twitter, Facebook and Instagram.