In my Clickbank account today, I noticed a sale from a publisher I hadn't seen before. I checked to see what the product was and it wasn't one I normally promote. Then I remembered doing a blog entry a few weeks ago about the subject and I had tossed in the affiliate link. It was just that one post referencing a product - that I picked out of Clickbank because it was relevant. I normally promote very specific Clickbank products - over and over again - blogs, articles, etc. But sometimes I will write something that fits my blog theme, but isn't too easy to relate directly to my normal product promotion. That is when I will find a new product and toss it in. (It could be another affiliate product besides clickbank, too.) This is what I call the Dandelion Technique, where I scatter affiliate product links here and there that I many never promote again. Now I don't generate the kind of sales that the more directed promotions do, but every so often, "Wham!" an unexpected sales occur. My point here, is even while you are pushing a particular product regularly, it doesn't mean that you shouldn't link to other products, even one time - if it is relevant to your subject matter. An unexpected $18 commission from a post that took what? 20-30 minutes to do? can be the prize.
I presume for this technique to work, you need to have an existing reader base. For someone starting out, I think its better to just concentrate on one product/niche rather than spread themselves thin.
I do have many websites and blogs to which I add content constantly. This provides me many opportunities to link to many affiliate products. My point is that I try to let my content suggest to me additional products to promote from time to time. Lets say I have a blog about milk and write about milk every week where I push a e-book about how to make yogurt and ice cream. One day it strikes me to talk about organic diary farming. This gives me a chance to promote an e-book about organic gardening, in that one post. My main goal is to write something interesting that gets some readers to return to my blog each post. But sometimes I get lucky and someone who likes milk is also interested in Organic Gardening and I make an unexpected sale... And don't forget that one blog post can be visited over and over again, a year from now... Certainly you should concentrate on your main niche products, but don't let it keep you from adding an alternate product here and there. A five minute search at the Clickbank marketplace can reap real rewards.
I also used this method before. I just submitted a video on youtube with my affiliate link at the infobox and forget about it. One day i receive an unexpected order for forex product with huge commission.