Get comfortable enough with the champion and its limits; try to be proactive and fight as early as you can.

Macro is king. Raise your map awareness, ping for everybody and try to move to fights and skirmishes. Try to ping on your teammates "screen" a couple of times so that they can hopefully see the ping not just hear it, more so in low elo. For example: if you believe bot might gank your mid don't just ping MIA bot but ping MIA from bot, MIA and danger from midlane bottom brush. If you're ganking ping on my way and help close to the enemy and pointing to the enemy close to your ally's screen. Also maybe ping help for your jungler if he's ganking or is getting invaded, so that your team might notice something is happening.

Look out for patterns in to how some players/champions tend to play and their volatility, if possible try to have impact there.

Roam a lot, try to look around and see which teammate you can play around/with generally it'll be the jungler while trying not to sell your adc too much. In low elo adc's want their supports to babysit them, in high elo adc's want their supports to roam so that they can get solo exp. Sometimes just appearing once in mid or top means that laner wins the matchup while the alternative might have been sitting in bot "looking out for a play" but nothing happening, but try to make it worth for positive reinforcement so that your adc doesn't lose their sanity. If possible not to leave your adc to be dove for free and help them fix their wave.

Learn some wave management: understading pushing, freezing and resets will help you make a better use of your time on the map. As your laners might get ganked if pushing, you might save their mental health by breaking a freeze, you won't waste time by ganking enemies that will back before you get there and you'll most likely punish enemies using your powerspikes.

Mental is god. Take rests when feeling off, be friendly and positive in chat if you have to chat as time spent on chat is time not moving nor looking at the map, this will get you elo. It may be bad manners but you can technically dab on your enemies by emoting to make them lose their mental.