Anyone who has been in Internet marketing for longer than two days knows that it is important to develop multiple streams of income.  Some beginning marketers can take this admonition too far, too quickly.  I have seen sites that have products for sale, links to affiliate's products and contextual advertising all on the same site.  Sometimes all three appear on the same page.

Before I describe a much more sensible approach, let me explain why a multi-purpose site works against a marketer's objective.  Each site, and certainly each page within a site, should have one purpose.  Eventually every visitor to your website is going to leave your site, but you want to be able to stack the odds concerning how that visitor will leave.

In a retail site, you want them to leave only after they have stuffed your shopping cart full of your products and completed the check out process.  The last page on your site that they see should be your thank you page.  All of the other time they spend in your store should be directed toward getting them to that page.

In the case of either affiliate marketing or contextual advertising, you want to move them off your website.  However, you want to move them in a way that brings you revenue, either in the form of a click on an ad or by going to your affiliate site in order to complete a purchase there.  The way you encourage your visitors to move to the site with which you are affiliated is very different from the way in which you make it appealing to click on a contextual ad.  Those two purposes can not be accomplished well on the same page and perhaps not within the same site.

Your job as an affiliate marketer is to convince your visitor that this affiliate's product can meet the visitor's specific needs.  You highlight those needs with your copy and point out the ways in which the product is particularly good at what it does.  You know the product well and can write specifically with that in mind.

You don't know (in most cases) what products or services are going to be offered on the contextual ads that are placed on your site.  Indeed, those ads will change frequently.  In your copy and design, you must meet the expectations of the visitor who came to your site with a purpose.  At the same time, you must let them know that your content has not answered all the questions that they should be asking.  Hopefully, one of the ads that appear on the page while your visitor is there will seem to provide answers to the needs that your content has stimulated within the visitor, so that she or he will click on it.

Each form of generating income requires a different approach to your content.  Any given page must have only one primary objective, if you are doing it well.  Remember, though, that many of your visitors will visit more than one page on your site by following your navigation.  If they encounter one page that praises your own product and another that advocates your affiliate's product, all you are doing is adding to your visitor's confusion and probably delaying any decision to purchase.  Instead, then, I advocate multiple sites in order to have multiple streams of income.  Do not try to build them all at once.  Determine which option has the greatest (and quickest) potential cash flow in your niche.  Begin with a site that builds that income stream whether it is to sell a product, endorse and affiliate product or deliver contextual ads.  You can create those other sites, later.

Here are two exceptions to my advice, above.  On your product site, you might want to use your thank you page to promote an affiliate offer.  I sometimes place contextual advertising on my links pages.  My thinking is that any visitors visiting my links have already decided to leave my site, so there is no harm having them leave me a little money on their way out.