The first place you want to start, when it comes to marketing your information products, is actually at the root of it all - your website. If your website isn't ready to spectacularly showcase your wares and move customers from visit to checkout, you will have a hard time converting prospects to customers regardless of how much marketing you do.
Your website should be simple, straight forward and contain a minimal number of links so as to not confuse your prospect. In Gerry McGovern's book, "The Stranger's Long Neck", he talks about how most visitors spend most of their time doing three-four top tasks. When someone lands on your website, regardless of how many options and content you have built into the site, they really will only act upon three to four things. It is your goal, as a website owner, to make those top activities the strongest they can be.