You need to make friends with alot of poeple, and make some relationships, share and contribute. On twitter make sure to follow back, and make facebook fan-pages aswell. Next is patience, and you need alot of that...
Check out this site for some ideas to write about: http://www.chrisbrogan.com/50-ideas-on-using-twitter-for-business/
i think twitter is the best site for marketing your product..but 1stly your must set your goals 1st...try to get your targeted audience and seriously you need to know the twitter marketing strategy and the twitter basic method to get the mass follower to do business in it