Create some content that answers one of those problems of your targeted market or look through the content that you have created and see if you have something valuable for your readers.
Then give them away in the form of ebook, special report, checklist, interview, podcast, video etc.
Just ensure that it is in a standard format that can be easily read, hear and view after download.
Remember that the content should demonstrate your expertise.
The free give-away starts your readers on the trust road that is imperative for them to travel before they decide to buy something from you.
Picture by rcade via Flickr, Creative Commons