I wouldn't touch an illegal substance period, but that's just me. 21 is still too young IMO, the test in your body is still sky high. Try 30~. As I alluded to earlier, a few of my friends from school toyed with steroids. One ended up with a hormonal imbalance, which needless to say is pretty serious shit. That's what steroids are - synthetic testosterone, more or less. It is relatively easy to inject too much. Your body responds to the excess testosterone by limiting it's own production, which is why people end up with smaller balls. Sometimes, this production never really picks up as to where it previously was, which is pretty silly because you're trading a temporary spike in testosterone for potentially a life time of abnormally low natural test levels. As somebody mentioned before, PCT is usually used to combat this, but what happens if your efforts are insufficient? What happens if you make a miscalculation? You're playing with fire, especially at this age.
The other one of the guys from school (not a mate) ended up accelerating hair loss. How stupid is that. You take the compound to look better but you end up irrecoverably (without cosmetic surgery) ruining your appearance.
There are heaps of people who are quick to tell you "yeah they're safe" but they usually haven't used them long enough to fully comprehend what they're doing to their body. "Bro-science" has its place in bodybuilding, but when it comes to something as hardcore as steroids I'd take it with a mountain of salt. A minority of doctors would tell you that steroids are safe. The catch is, they usually recommend you take them under medical supervision, which you obviously can't do in Australia unless you have a genuine reason (which nobody in this thread appears to have).
In addition to this, God help you if you end up with a dodgy substance or something that has become contaminated (happened to a dude at the gym and saw him hospitalised for a week).