you have a ton of natural test being produced in your body right now... so why spend the cash for it and then unbalance your system... ie shut down that natural production and have to use meds to get it going again... I personally waited till I was 26 (that's not to say I wasn't training I wrestled in college) I'm glad I didn't jump in too early... I am by no means suggesting to you to wait that long as if your training/diet and knowledge is good to go... then by all means begin but not for a few more years... I would suggest 21 as minimum age and that seems to be the general consensus... it's just when you start using you begin to play god balancing and unbalancing the natural order of your system... and right now you system is in peak form so a good diet and good training will do miracles!! just an opinion... as you are 18 now and you are your own man... but be a man that uses wisdom... and there are alot of folks here who have been in your boat... and your best ally is open ears... because there are folks here relaying knowledge and wisdom from their own personal experience having already used gear... but as previously stated.. you are your own man... good luck with it all!!
~Papa Lion~