One of the most important things in this game is money managment and coordonation with your team. When one of your teammates says "eco" it means that you have to spend all of your money no matter how little you have.

Now that you have learned the basics of economy let's get into the weapons' part of the game. Even though there are many weapons available you must always only buy good and consistent meta guns.
I personally recommend avoiding the Rifle category as most of the guns there are useless and unoriginal, if you pick up one of these "pea-shooters" you should immediately drop it outside the map as they spread cancer.
The best category to choose your weapons from is Heavy , the guns there are extremely good and cheaper than the bad rifles.

As this game is a team-based one, you have to constantly communicate with your teammates. One good practice to do in-game, especially when playing with strangers but works with friends too, is to loudly complain every time you die and blame everyone else except you. If anyone complains just vote-kick or team-kill them.

If you have read and followed everything in this guide then you are officialy not invalid.