Hey, Nick.
Right now your avenues to meet people are probably kind of limited. That's not your fault because up until age 18, most people live in the same place without seeing much of the world.
If you plan on going to college, your possibilities will begin to open up. Support groups, social clubs and ad hoc clubs that are LGBT friendly are becoming much more common on campuses all over. Obviously the abundance of social media sites makes it easier than ever for you to seek out and find other gay males looking for all sorts of things: one-night-stands, relationships, friends, FB's, etc. There is no guarantee that you will NEVER hit on a str8 guy. It happens frequently and aside from feeling a little sheepish (and unless the guy is a TOTAL homophobe and tries to physically harm you), no harm, no foul. Some people develop a rather keen sense of intuiting others' sexuality (aka "Gaydar") but in case you don't have that (I'm gay and I think I was in the bathroom when they were handing out the Gaydar units...), going to places/communities/groups where LGBT predominate will greatly increase your chance of meeting someone.
The trick is: to find LGBT communities and places where LGBT concentrate and throw yourself into mix with a positive attitude. Not many people like the moody, high-drama, high maintenance kind of BF. PRIDE parades are a great way to be out there in the crowd and to start broadening your horizons. No one is BORN with the knowledge of how to meet people or date or know where all the cool LGBT places are. Be curious, ask questions and your LGBT brothers and sisters will take care of you.
Generally speaking, your larger metropolitan areas are going to have a better chance of having an LGBT enclave somewhere in the city. Cities like NYC, Chicago, LA, San Francisco and Seattle are obvious places but ANY city of size--Columbus, OH; Milwaukee, WI; Miami, FL; Philadelphia, PA; Portland, OR; Minneapolis, MN; Phoenix, AZ; Indianapolis, IN; Atlanta, GA; Orlando, FL; Des Moines, IA--all have their pockets of LGBT which are thriving communities. The LGBT folk in smaller towns may not be as visible because "reputation and private lives" are more guarded.
Don't worry about meeting someone! You're only 18! You have a LOT of years ahead of you to find your special someone! In the meantime, enjoy the ride!