Ranking normally in the game can be quiet slow and tedious process . High rank players will melt you with their superior weapons while you are stuck with weapons that cannot shoot properly . Keeping in mind that a lot of the game veterans know how to exploit the game and even make it virtually unplayable .

So what you can do ?

1 :

Playing singleplayer is not a viable option . The experience you get doesn't synchronize after you leave your local server . It must be multiplayer over the internet . Playing against bots only over the internet with bots only is not the best option . Sometimes you get no permanent experience . You need to play with humanplayers .

2 and most important :

Most important thing is to always pick the winning team . Forget about team ballance ! Going for team ballance is not good for you on the long run . Don't worry about the other players . Besides a lot of them are trolls and the like . It is a very toxic community .
A lot of old players want you to be low level as long as possible in order to have their cheap fun and abuse you .

3 :

Don't let them to persuade you to change team ! You need to be hard with the other players if you are planning to play the game for long . Even if they call kick or even ban vote . If you see it in time which you should - it is a huge transparent box that appear at the bottom of the screen . Leaving the server before times runs out nullifies the ban/kick . You can reconnect to the same server if you like - a bit less experience (or a lot if you got forced to leave after 2/3 of the game) . But such votes a rare and even if you receive such a vote against you most likely you won't get another one .

PS There are even famous cheaters who tell people to go in the opposing team . But when their team wins they say nothing about team ballance , wondering why ... Insolence and hypocrisy are on another level in that community .
You will figure with time who they are and you will see them cheating with sure . But don't let them persuade you with their lies the first time you meet them . It is your funtime and your game experience they want to ruin .