How to cheer my team up,,,without being annoying ?

Keep things short and to the point.

We scale Aim for this player Protect that player Avoid arguing with teammates Acknowledge good plays

It lets your team know that you still want to win.

Be funny

"Welp, we got aced but at least we're all handsome"

"Push! Push like it's labor! I can see the head! It's a boy!"

"I was getting dry humped by a ninja, an edge lord and a pirated for 15 minutes. Sorry if I'm a little behind"

Note: Damn, I'm really sarcastic about things

Be funny. Make them laugh. When they do something silly or dumb, make a joke or say "at least you didn't do [something funny here]." Give a lot of "xD" faces, etc. As a support main, my job is more moral support than anything else. If you can make them laugh, they'll feel better.

Self deprecation is good too, "Ezreal, bby, you gotta carry me. I'm so bad." Blame yourself in chat when anyone dies. "Riven's obv cheating. Mega hacks." It makes them feel like they aren't being blamed, and can come back from it.

Note: Sometimes this results in them actually blaming and flaming you. The moment that happens, mute them. It's not worth getting tilted over.

"How do I-"

IT'S NOT THAT HARD, PEOPLE!

Don't even try.