For me, i wish someone would have told me not to inject delts every time. i have so much scar tissue there i don't think i'm going to be able to use them anymore.
i wouldn't have used synthol in my delts either, i'm pretty sure i got most of the scar tissue from that sh*t.
i would have done pct after my first cycle, crashed bigtime and almost ended it permanently.
i would have taken my time injecting instead of being in a rush, that's when you do stupid shit like injecting w/ the needle you drew with, or using the same needle twice...
i'm sure there's more but i can't think of any right now.