What kind of support do you play ?
if you play an enchanter : try to play around the one mate that is the most fed in your team. he will do much more, ennemies will try to focus him down, and the rest of your team has more air to play. If no one in your team seems fed enough and they're all at the same spot, then switch your focus to one ennemy. Imagine you are Janna, and they got an irelia, your job is to fuck her up with tornados and ult. Focusing only 1 ennemy is easier to do, and you really can negate her entirely.
if you play an engager/roamer : try to do intelligent roams, and go for free kills (there are more than you would expect). Always engage 3v2's or 4v3's, things like that
Most importantly, get vision control around places you know a fight will occur. dont hesistate buying control wards, and if you are full stuff, don't buy a 6th item, rather 3
. Vision allows you to know when a move is free, if you know where their jungler is when you start engaging, etc.
Try running Exhaust instead of Ignite. Low elo soloqs often have one really fed dude, that gets completely shut down by exhaust. Everyone is playing Ignite atm, so most people forget about exhaust and mindlessly go in, but get denied so hard.
and finally : always be positive, always say "gj" when a good move happens. Psychology is more than opie op in this game (:
hope this will help !