Your website should at least provide users with some valuable information or services. It will be unlikely that your site gets accepted, if it consists primarily of advertisements, and/or affiliate links.
If your site is a link directory, or primarily consists of links, then it won't be accepted. This would go in the category of providing quality content on your own, links is rarely considered content on its own.
Make sure that links on your site are working, and that your site is easy to navigate on. The contrast between elements on your site should be easy on the eyes, and should clearly separate non-textural ads from the content.
Don't use images for everything on your site, and especially not the textual content. If you are using images, make sure that the contrast between elements isn't to high, and isn't to low.
Ads should not be placed to near navigation links, and other click-able site content.
You should limit the use of scripts, to the places where it makes sense. Using scripts for layout purposes is bad, and if you are doing so, the rendering of your site shouldn't be delayed, and/or suffer from performance issues as a result.
Make sure your site doesn't break the back button in the browser, and your links doesn't force the opening of new windows, unless it makes sense for your website to do so. I.e. Individual smaller functions.
If you use Mechanisms to get around popup blockers in browsers, your site won't be accepted. For example, Some sites will "fade out" with an ad, displayed for a limited time, and/or until the user closes it. Your site won't be accepted if they uses such mechanisms.
It should be clear who the owner of your site is, if you want to be taken more seriously. About pages is an easy way to tell some more about your site, about the owners, and where your headquarters are located. You should also provide users with some way of contacting you.