Talk to people, like you're doing here by posting this question :) Nice job putting yourself out there and taking the first step! In addition to talking to people, read about the experiences of other people who have successfully done what you think it is you'd like to do.

Think about your passions and don't be afraid to follow them. However if you do, make sure you can build a viable business around them first, before throwing your valuable time and your or other peoples' resources at them. Do this by validating your business ideas as you dream them up.

Understand that it's possible to make a living and be happy doing it. I'm just learning this at age 42 and kind of wish I learned it sooner :)

Find a supportive mentor or group of mentors. Find people who are supportive, yet will still challenge you. While you want people who will support you, you don't want people cheering you on as your continue to run full speed off a cliff ;) These people may be your family, they may not be your family, be open to both options.

Keep an open mind. Don't be afraid to fail, learn and start again. At the same time, understand that success is possible. Surround yourself with people who think this way too.

Give as well as take. Help people that you can help along the way, without expecting anything in return.

Time is your friend and at 18 you have a lot of it ahead of you. Use it well and best of luck to you on the journey!