Hey there - Gold/Platinum/Diamond support main here - I'll offer you 4 pieces of advice: Goodluck!
1.) If your playing any sort've assassin, you should really try to let the tanks initiate. Remember that you are always a target. Going in first is dangerous, even if your as slippery as Fizz. Based on your above scenario, I believe you could use help with positioning. This is a critical lesson. I have a goal for you - Attempt to die less. specifically,** try to die no more than 5 times per game**. I want you to look at my deaths in my match history, then look at yours. One of the biggest things that separate platinum and above players from the rest is that they have figured out how much a death really costs them. In short; you are dying way to much.
2.) I'd suggest picking a favorite 'in-meta' champion and trying to master them exclusively. It allows you to focus on other aspects of the game, and you'll learn how to overcome the champions shortcomings by beating bad matchups. When you get comfy with a given champion, you can start focusing on all other aspects of the game like enemy champions, who is fed, who is weak, warding, objectives, CSing, ect ect.
3.) Focus on YOUR OWN PLAY. Have an internal goal each game - and it can't be 'I want to win' ..It needs to revolve around your own play - like 'I want to die less than 5 times' is a perfect goal! or 'I want to have item X by 15 minutes' is another great goal. If you only focus on if you win or lose, you will burn yourself out and become frustrated. Each game, play to YOUR OWN PERSONAL BEST. Did you win? who the phreak cares - how many ultimates did you land? Focusing on the details is what will make you a better player, especially over the longer term. If you played your absolute best and still lost, then you probably had an awesome game - and ultimately - that's what it's all about.
4.) You seem to like the diver assassin archetype here, so my final piece of advice is to be more mindful of objectives, rather than kills. Pushing is your ultimate goal. Getting fed is great, and that will DEFINITELY let you carry and win games, but too often these types of players get carried away, and make bad plays because they think they can score a kill because they are fed. You can single-handedly put a team back into the game by making a bad dive and getting caught, even if you get the kill. So in short, calm down - be still like the waters, and let your enemies make mistakes. Don't risk yourself for needless kills.
