I also still struggle with this myself; however, more so when I play with a heavy tank due to its reduced ability to relocate.
In any case, I find the vast majority of games are quite uneven skill wise. This means that one team will often beat the other handily, and quickly. If I am on the disadvantaged team, I find it difficult to stem the bleeding on my flank before we are completely overrun and destroyed. On the other hand, if I am on the more stacked team, I find it difficult to keep up and get in enough damage before my team wipes the enemy team away (again more so in heavys because I can't keep up speed wise). The most ideal game is one that is close, but where my team is losing by a small-ish margin, that I can recoup with good play. Those are very few and far between I find.
It's a difficult balance to find the right level of aggression and conservatism, especially because I only solopub and relying on teammates to push when I do is unrealistic 95% of the time.
That's why when I watch replays from a guy like Kewei I find it hard to believe he can be so aggressive and not get smacked by arty or let down by teammates more than he does.