Have no idea? No problem, spend 2 to 3 hours a day and subscribe to podcasts of "wild" thinkers such as: Tim Ferris, a16z, the startup chat, art of charm. Listen to them for a week you will have a clearer vision or idea of what the next step should be. On contrary to all belief do not rush yourself, have more fun and party more you are only 18 once ;)
Work can always wait...