.....Alright dude, I guess I'll be that chode to post the last thing I wanted to read when I started on the forums (elsewhere, as Im pretty new to evo). In a nut shell, at 21 you're a grown ass man and will do what you desire. this is America and I respect that! However, just one guys opinion, though I would roll the dice and assume maybe a few of the boys will agree, you don't need gear yet. With your frame, which by the way congrats as I'm 5'8" on a good day, you have a lot of filling out you can do, most of it naturally. 4 years killin it is a solid base and a positive learning attitude is huge. Just consider maybe waiting a few more years before taking that plunge, in that time you'll have learned that much more about yourself and how to respond to different diet and training programs. You'll have gained that much more strength and training capacity, and will be able to benefit from some special supplements that much more. Understand at 21, the average dudes nads (especially an active, healthy, young buck) are producing more than enough test to support strength and muscle gains.
If you do decide the risks of possible endocrine system issues (necessary HRT early) are worth it, you're willing to poke on schedule, have your meals packed every day, stick to the diet, destroy everything in the gym, neglect partying and chasing broads to make sure you're at home gettin the proper rest, then please do so as safely as possible. As you already acknowleged, theres a ton of guys on here with a wealth of knowledge and are more than willing to help, us the resource and learn as much as possible. When it's all systems go, mak sure everything s in hand, and everything is prethought out and planned to the T. Already have a contingency plan if you start noticing a little titty growth/sore nips, if your BP jumps, etc. As with anything, measure twice cut once, particularly with something like sauce.
Lastly, and I'll hop off my soap box and quit preaching, please, please, please get blood work done! Before to know where you are now, during to make sure estrogen, lipids, etc. are reasonable, and then a while after to make sure all went swimmingly and your HPTA recovered. As much as I believe theres an instincual aspect to gear and training, etc.,you really don't know whats up inside without a solid blood panel. You hear of guys having cardiac events, sometimes fatal, may God rest their souls, when they were seemingly healthy and said they felt great. Some things are out of control with sh***y luck and whatnot, but mabe if they had followed up with things, taken more of an interest in their health and made adjustments or started meds or whatever, they might still be here.
Whatever you decide bro, be safe.