Economy management is definitely one of the hardest concepts for new players! If you want to really understand the fundamentals, you should
go over here where there's detailed explanations of how the money system works in competitive matches. The key is coordinating with your team rather than making individual decisions. Learning when to force-buy, when to save, and how much money you need for full equipment takes practice. Understanding armor economics, weapon values, and round loss bonuses will drastically improve your game sense