What should I do if I am new to League of Legends and always lose in ranked games?

Since you are so confident, the main problem should be the lineup and teammates.

Lineup:

For example, on your side you have Fox, Teemo, Captain, Nightmare, and Bear

On the opposite side - Snake, Male Gun, Monkey, Mumu , Niutou

Then how do you NB in ??the middle? If you team up and others control a bunch of them, you won't be able to win. Even if you are ahead by more than 10 or 20 heads in the early stage, when the problem comes together, what do you think your side can do to fight, so in the future, you need to choose the lineup well and have more control. And there needs to be more meat. Just for this example, there are monkeys, Mumu and Ox heads on the opposite side. 3 meat, even if you drop the snake girl and the male spear instantly, how can you kill 3 meat? Especially nowadays, it is popular that F damage and T damage are too much, so the key to the lineup is control and tank.

Teammate:

There is really nothing you can do about it. Play more matches. Once you get to the first round and feel that someone is NB, add him as a friend and ask him if he is willing to play in a double queue. This will be better. OK