Nearly everyone in this business has sponsored links or ads on their pages (and if they don't, they're missing out!) Few people, however, are exploiting the full potential of these programs...
Freshness, placement, size, relevance, serviceable market, and even COLOR can affect how well your sponsor program is working for you. Let's address some of these.
If you've found a sponsor program that is working effectively for you week after week, then by all means leave it alone. However, if you're like most of us, you'll want to cycle through different banners that the sponsor provides, so that your visitors aren't seeing the same old stale ad every time they come to your site.
It's obvious that a banner towards the top ("Above the Fold") will convert better than one towards the bottom, in most cases. But a strategically placed banner right next to some juicy (and often viewed) content will also work very well. Pay special attention to the flow of your site, and make sure the banners hit them when they're ready to convert.
Small banner, or large banner? Depends on your page's setup, and which will fit into the mix. Not many look at big huge gaudy banners. I scroll so that I don't see them at all, if they're an eyesore.
Not many people will click on a teeny tiny banner shoved off in some corner either. You have to strike a balance between size, placement, and flashiness. It can be done, trust me.
What are you selling? Guys in clown pants screwing midgets riding unicycles? You might not have a very broad market, if that's the case.
Penis enlargement pills sell primarily to me. Dildos go to women and gay guys (or straight guys who want to get with either of these categories). Think about what market your site is drawing, and market to them.
Think about what market your site is drawing, and market to them. If your site caters to ebony, sell ebony sponsors, etc. Sometimes, it helps to sell gay materials on straight sites, but it usually DOESN'T work to sell straight materials on gay sites.
Hope some of this helps. I'd love to have input from some other people on this. Shoot out some suggestions by posting on the thread below: