Hey there R04R, thanks for stopping in to the thread.
To be truthful, my first cigar was when I turned seventeen, a garcia y vega gas station stogie. Horrible, btw. For one of your first, I would suggest something fairly cheap, but good. Most noobs like to start with a Connecticut shade leaf wrapper, since it's fairly mild, but with a sweet flavor that most can pick up over the smokey overtones. My personal recommendation is to get yourself an Oliva Connecticut, a Nub Connecticut or a Cusano 18. These are fairly widely available, so if you find a local cigar shop in your area, they will most likely have one of the three, and the great thing is that most of these are between three and six bucks. Pick up a cheap cutter so you don't get too invested before you know if you'll like it and light it with a wooden match if you have access. Sit yourself down on a nice night with a glass of water, coffee, or tea (preferably) and light it up with a few friends or family members. If you like it, welcome to the hobby, if not, you have a great experience for your 18th birthday.
Cheers and happy smoking.
Zach