But there's a more immediate way of getting some affiliate cash, and that's by tweeting your links to Twitter followers. You can use this method for most programs, but I think that Amazon Associates is by far the best suited. This is because no matter what your interest you will find countless excellent books, videos and other products that your followers will find relevant and interesting.
And Amazon makes this really easy to do. When you log into your Associates account there's a little button that creates a link with your ID included. It displays a summary that will show the product image and description.
Books are particularly good for this method. That's because the product pages are interesting reading in themselves. The titles automatically become your tweets, and these often contain keywords that people search for often on Twitter either on their own or as hashtags. The cover images displayed in the summaries are often striking, and give life to your Twitter stream.
When choosing products to promote relevance is key. No point in tweeting links to computer peripherals to tweeps who are into opera.
Subject matter isn't the only criteria, however. If you have a lot of followers from your own country, as many Twitter users do, then you're sure to get some clicks and the odd sale if you tweet geo-specific titles with general appeal. For example true crime, sport, and fiction books can all be popular if they relate strongly to your country, or even city.
Keep an eye out for trending topics, particularly those with their own hashtags. You can often get a higher rate of clicks to products that relate somehow to a story currently generating a lot of interest. Obviously this approach can get a bit mercenary -- even ghoulish -- in some cases. So you want to be mindful of this. (You might want to avoid using mass murders, celebrity deaths, and similar events to generate income -- although I suppose that's what the mainstream media is doing anyway.)
And you don't want to overdo it. If you constantly tweet product links your followers will start to get annoyed and some will unfollow you. So I would say that one in ten on average is fair for most categories.
I think you can make this a higher proportion when it comes to books, though -- especially if your niche is followed by avid readers. Twitter accounts related to current events and politics certainly apply here.
And no matter what niche you are promoting, always look for products that have some good reviews -- preferably from verified purchasers. You can be sure that you're recommending good products to your followers then. That helps build your reputation, which in turn makes it more likely that people will purchase after clicking on your links. So, don't just tweet a link to something just because it costs a lot and will therefore deliver a chunky commission. Make sure it's really good quality.
And on the subject of cost: Needless to say people are more likely to buy something on impulse if it's only a few bucks. This is why Kindle titles are idea for Twitter sharing. Sure, the commissions are small. But they come in more frequently than ones from, say, hardbacks and they certainly add up over time.