Each different model has its up side and down side and it is up to you to choose which thrills you most.

1) The Google Cash Method
This model is quite straightforward and the way it works is for you to buy advertising space or PPC advertising on a Search engine and send the traffic directly to the merchant with your affiliate ID. If the person buys, you will receive a commission. There are several downsides for this model; the biggest is that once you stop advertising your sales end too. Other downsides of this model are: That you have no control over the merchant's sales page, campaign effectiveness is pretty difficult to track and you are passing on a buying customer which you can never sell to again. Please note that this is a very easy model which has worked for many people. My problem with this model is that you are leaving money on the table because you are missing on either the back end sales or the future products you could have sold to this person.

2) The Landing Page Method
This model requires a bit more work and investment, but it also has long term benefits. For this Model you will build a landing page or review page where you write a quick review for 3 to 5 products and each of them will have a link to the product page. The advantage: The user has several products from where to choose, when your site gets picked up by the search engines you'll have free traffic and because it is a comparative review the product will be more credible by the time the user lands on the purchase page. Downside, you still have to pass through the merchant's sales page, you have little effectiveness tracking at the keyword level. You pass the customer on to the merchant.

3) Squeeze page method.
Here you create a squeeze page for a niche and either offer a free report or e-mail course where you can recommend your affiliate products. Advantage, great for list building, you can separate lookers from prospects, you can successfully continue selling them if they don't purchase your first offer.

4) All In One Automated Method.
To me this is the best model to follow because you have all the advantages of the previous methods. You have great tracking, a constant monthly recurring income, landing page flexibility, list building, and more. If you are very Internet Savvy and know some php you can do this yourself, except for the recurring monthly income, for that I strongly believe you would have to hire a programmer which would increase your investment quite a bit.