I would invest in Instagram advertising. Your target market uses Instagram heavily, so this will be an effective use of advertising dollars. Any kind of social media advertising will get you exposure with these age groups. You might set up a twitter account if you haven't already. You can promote your tweets and get your site out there. Maybe offer some kind of promotion for retweets, or special service or discounts through tweets that only your followers get or are eligible for. If you want an example- @HiddenCash on twitter. Hidden cash gains followers by tweeting out clues to where the cash is hidden in various locations. Best of luck to you!