I need help how to improve

I am currently Platinum 1 ( I alternate between plat 1 and 2, but plat 1 at the bottom is average) and am looking for some help on how to improve. I do understand that wherever you are at, that's where you are going to be until you improve. I just don't seem to be doing that at all really. I feel like i'm just at a stand still. I would like to make it to at least Diamond 5 before the season ends so i can get that cool border. So if i can get any Diamond 5 - Challenger Tier tips or coaching in game, that would be great. Thanks.