There are endless free to join affiliate programs available on the 'Net — in any category you might be interested in.

And joining an affiliate program is without a doubt the easiest way to start earning an online income.

Here's how it works.

You become an affiliate for another company's product by joining their free affiliate program. Then you promote their products or services on your website. Anytime someone you refer buys something from them, YOU get paid a commission.

And the best part is that it doesn't cost you anything to get started!

Most good affiliate programs will offer you free resources to help you promote their products effectively. Things like banner ads, salescopy, or product photos that in many cases have already been tested and proven to work.

You simply download them and use them on your website.

Why are they willing to do this?

Well, the better YOU are at promoting their products, the more visitors and sales THEY'LL receive. So everybody wins!

You're helping them get customers that they might not have been able to get otherwise. And you earn money for doing so!

The amount of money you can earn from affiliate sales will depend on a number of factors:

Commission amount. Companies will offer anywhere from 5% up to 50% of a product's sale price — a BIG difference.

Price point of product or service. A higher price point means a higher dollar amount for you, depending on the commission. This should be balanced with the commission amount.

Potential volume of sales you can make. Some highly specialized products can sell far more infrequently than others, limiting the number of sales you can make in a given time period.

How effective you are at promoting their products. The amount of time and effort you're willing to put into promotion is a HUGE factor. Techniques like building an opt-in list and using email marketing to build relationships with your site visitors can catapult your earning potential.

There are a number of ways to find free affiliate programs. But if you're just getting started, you might want to check out affiliate directories like AssociatePrograms.com and AffiliatesDirectory.com. They provide lists of credible free to join affiliate programs that have been pre-screened.

You can also sift through websites that sell products you're interested in. They'll tell you if they have a program they can join.

As an affiliate, you earn a commission for any sales made by people who click through from your website and purchase an affiliate product. So making money with website affiliate programs is dependent on maximizing the number of sales your site visitors make.

And in order to maximize sales, your website needs traffic -- and lots of it!

Here are some techniques that will help you send visitors to your website:

Achieve a high ranking in the search engines.

Make sure your website includes keywords that target your particular market. When the search engine "spiders" come to index your site, they'll boost your site higher in the rankings for those keywords. Ideally, you want your site to show up on the first or second page of search results.

Write short articles that will be distributed all over the Web.

All that's required is about 400 words on a subject related to the product you are promoting. Include your byline and a link to your website at the bottom of each article, then submit them to free article directories, like EzineArticles.com.

When other site owners who are looking for content for their own sites republish your article, your name -- and site link -- will be propagated all over the 'Net.

Buy pay-per-click traffic.

One of the fastest ways to drive additional traffic to your site is by advertising with pay-per-click search engines, like Google AdWords. All that means is that your link shows up in the section for paid advertisers. Then every time someone clicks on your link from a search engine results page, you pay a pre-determined amount.

Build a list of visitors' email addresses.

This allows you to contact your visitors again with valuable information that will lure them back to your website. Or, you can even promote affiliate products directly by email.

It's a great way to build relationships and trust, which translates into more sales over time.

Once you've got these tricks working for you, it is much easier to start making money online with affiliate programs.