My company is a well-funded, incredibly niche technical startup.
With 17+ years in PR, and my work as chair/co-chair with the MIT Enterprise Forum in Chicago, let me add to what has already been said.
You have two industries (aka targets) to approach - technology & advertising. Try to include a demo video in your media pitch/kit.
Create and tell a story to reporters as to why you created your startup. What need did you see? Is it from personal experience in the ad industry? Something you experienced that was a real pain. Something that you said to self "there has got to be a better way."
Find out from your financiers who they have funded and then research to find out which reporters wrote about those companies. I would also suggest putting out a press release. PR Web is relatively cheap, and can help with SEO. If you need a media list I also have a suggestion. Feel free to contact me.