Cost per action/sale methods require that referred visitors do more than visit the advertiser's website before the affiliate receives a commission. The advertiser must convert that visitor first. It is in the best interest of the affiliate to send the most closely targeted traffic to the advertiser as possible to increase the chance of a conversion. The risk and loss are shared between the affiliate and the advertiser.
This is the easiest way to gain experience because you get exposed to other affiliates. You can meet people by joining a discussion forum or an online community. The good thing is that they are free to join and you get very good advice there. Examples of such online communities are ABestWeb, Digital Point, and Warrior Forum. Apart from getting advice from more experienced affiliates, you get the chance to network with other marketers.
Always disclose your affiliate relationship. Most visitors will probably understand that graphic ads will lead to your getting paid, but if you write a review or use an in-text link as a recommendation, you want your readers to know that may lead to compensation as well. This ensures you retain transparency and trust with your readers, but also, it's required by the FTC's endorsement rules.