First, you will need to know how to pick out the correct articles to make your sites successful. There are many types of content, from free content to high dollar content, and each comes with its own advantages and disadvantages ( although high dollar content is more likely to give you a successful site in the end ).
Second, you will need to know how to choose keywords that can help you get a good amount of traffic, without being too competitive to get on the first or second page. If you choose highly competitive keywords that are used by large, mammoth website, you are likely to never get up to those much needed first two pages.
Third, you will need to know how to optimize your websites for various search engines. Search engine optimization skills will allow you to get high rankings for your chosen niche keywords, which will help to get visitors and make profit.
Fourth, if you opt for a large website that you will focus most of your internet marketing career on, you will also need to know how to market your website to your intended audience through paid banner ads and text links. If you prefer very small 2 - 5 page niche sites, then promoting all of them this way will not be cost effective and will eat up more profits than it is worth.
If you can capture some of these skills and attack them aggressively during your first few small websites or the first few months of a larger website, then you will eventually become an expert. Since you can learn the ropes first hand on your own, the only thing that you will need to do before you begin your new career is to read up on how to get started ( maybe purchase an internet marketing e - book or two ) and make sure that you have the funds available to start a small site.