Play Safe when you have Flash down
A common mistake I see in low elo, especially as a jungler, is when people play unsafe right after they flashed. It happens more commonly than you'd think, basically because they got killed (or rather used flash, sometimes both, which if so, I pray for your unfortunate soul) because they were overextending in the first place, so they're bound to do it again, except this time they have no escape mechanism.
So sit back in the middle of your lane, don't push, unless you can push like a crazy man really quickly (azir) and make them miss cs under tower cause they're badies.