There are many jobs available in internet marketing. You could be a search engine expert and help company build their websites.
Some companies use pay per click method i.e each time their advertisement is clicked on your prolife or website or blog they will pay you. This gives you a neat profit and helps the companies increase traffic on their sites.
Google ad sense is also a very popular tool. In this Google places advertisements on your sites and you get paid for the traffic you generate. Therefore it becomes important to have interesting site, a interactive blog and a good profile.
Never go out in the market unprepared you may be caught off guard and the valuable first impression will be lost.
Some advertising agencies may hire you to promote their site and product on your blog or site. Remember you cannot sell everything on internet. So choose the products you recommend wisely to get maximum traffic and response. Some customers are uneasy about buying things on internet  because they are not comfortable with the amount of personal information required. Build a site which does not cause these kind of concerns.