Hi, you can try PTC sites like Neobux, grandbux etc. I don't think adwords is a good option. Between you can also launch a bounty, where Bitcointalk members can carry your banners as signatures or just advertise on Bitcointalk. That's a better targeted audience.
In my experience PCT burn your money. You could only recrut users with another PCT and BUX site. You would also build a bad reputation. Bitcointalk is really the best option to get your pre ico visible as preposter already stated because you reach the most interested users, who even search for interesting ICO projects.