Make League great again!
Recently I've been having a lot more fun during matches for a couple reasons and I'd like to share some of those tips.
Find a duo buddy, IRL if possible. League has millions of players, find someone who enjoys casual play or competitive play, just party up and have some lan parties :D
Change it up: A fun game we do is my duo buddy picks my adc for me. I main adc and I own all of them so he picks a random one I haven't done yet, and I pick their support that hasn't been played and we have fun. We even do casual troll lanes like Kennen-Annie bot.. so much fun XD
Try weird shiz, thats semi-viable. You don't want to take champs where they absolutely don't belong because the chances of you doing good are pretty low and no ones happy after you feed a trolly pick. Pick someone un-orthodox but not completely crazy!
Play matches again with people IRL. Staying in a room with someone doing league is a great help to not tilt.. or to tilt together and rage at the same champs and plan their demise!
In general be nice and kind to your team even if you're losing or if they're doing bad. Losing sucks hard, we all hate it (Usually... lookin at you trolls out there) If someones losing, they're guarenteed to be a little upset, don't tilt them ok :D