Follow the instructions of your chosen PDF maker to format your ebook. Be sure you include a page at the front and back of the book that lets people know how they can sign up for your newsletter.
Put your ebook up on your site or blog. If you've been building traffic to your website, this should be one of the first places you distribute your free ebook because you can track your stats more effectively.
Use an opt-in newsletter such as Vertical Response, to capture email addresses and build your list. You can choose to make this a requirement to get the download from your site, or make it optional.
List your book on free-ebooks.net. Free-ebooks.net has a massive audience reach, giving you the opportunity to really grow your customer or reader base. This is especially true if you take advantage of some of their advertising opportunities to give your ebook top placement.
Upload your ebook to smashwords.com. Smashwords has a unique system allowing you to convert your ebook into many different formats that readers can download from the site. They also have a premium distribution channel you can gain access to just by following their style guide. You can distribute your free ebook through Smashwords to the Sony ebook store, Amazon, Kobo and barnesandnoble.com.
Distribute your ebook in as many additional places as you can find. The more varied your distribution, the greater reach you'll attain. Ideas for other sites to upload your ebook to are Scribd.com, Obooko.com and Manybooks.net.
Use social networking to market your free ebook further. If you've built a presence on Twitter or Facebook, use this to your advantage to distribute your free ebook. Encourage “retweeting” (when other Twitter users share your message with their friends list) by offering prizes through random drawings for those who retweet your message.