WHAT DO I NEED TO DO TO NOT GET USELESS TEAMS EVERY GAME?

You get teammates and enemies who have similar performance levels to you. So if you want to get better teams, you're going to have to increase your performance level and climb.

play vs AI

it happens every game for everyone, another reason is because your opponent is far superior (it ends to match up a team full of 40% win rate players vs 50~60%+ it just shows how screwed up the mmr is and how it does not work.)

there are also plat/diamond/master smurfs and illegal rank uber services that ruin the ranked even further.

all these smurfs and ridiculous burst meta forces newbies to get slaughtered until lv.30 and what they do is jump straight into ranked thinking they're ready for some reason despite not knowing how to cs nor know how to win the game which is why the quality of ranked gets worse and worse every season.

there is too much benefit for rolling smurfs or buying/selling ranked accounts etc (this should be illegal tbh..) there would be far less smurfs if ranked decayed faster.