Before you take action, you should have a goal. Not "I want to make money through affiliate marketing" or "I'm going to flip sites for profit." A REAL goal. If you want to try affiliate marketing, what is your first niche? Are you self-hosting or setting up a free site? How are you going to drive traffic?
Do not get caught up in the specifics just yet. That is for later when you are split testing and analyzing your figures. However, knowing these few simple things can save you many headaches down the road. After you have an idea of where you are going and how you would like to get there, then you take action.
By making the decisions early on and having an idea of how to get where you want, you can optimize your research and learning as you go. Instead of having a vague idea of how to execute a marketing strategy, you will be able to make decisions and changes with accuracy. True understanding of the effects caused by taking action is the only way to ensure that you will get the results you desire.
Anyone can throw ideas at the wall until they get lucky and something is successful. But they will never repeat that without another healthy dose of luck. By refining your skills and having a plan, you can replicate your success time and time again and really reap the benefits of your efforts.