Before you play ranked...
think a little. Luckily it's only preseason. However, these things still happen when the season starts. If you're going to play support, actually be a support. Don't ditch your adc to run after the support to get a kill because you're feeling greedy, only to have your adc, then yourself killed. If you're going to play jungle, actually gank a lane that needs help. Don't stay in jungle for 15 minutes while you have losing lanes. If you're going to play adc, at least know how to last-hit, and make sure there is no ability power or magic pen in your rune page. I see too many trashbags in these 3 roles the most. If you can't do the above things, fuck off out of ranked assholes.