I would say practice as much as possible and start building a portfolio! If you do people's make up, be sure to take photos before and after so you have a portfolio of your work! It can definitely help you get internships/jobs in the future! You can also look to be an apprentice/intern for a more established makeup artist. Good luck!
I started playing with makeup as a teenager and had a passion for it. It sounds like you do to. Practice on anyone who will let you. Lol. Check out some salons in your area for an experienced makeup artist who might be willing to be your mentor or offer an apprenticeship. I had wonderful mentors and they taught me so much.
Kevin Aucoin was a wonderful celebrity makeup artist and his book on makeup artistry is worth buying. Hope this helps. Keep doing what you're doing and it will all come together.