Most rounds in Valorant are decided before anyone fires, by whether your team brought enough to win the fight it is about to take.
There are only four decisions, and the hard part is that they are team decisions wearing the costume of individual ones.
The four calls
Full buy. Rifle, full shields, and the utility your role actually needs. The round you intend to win on equal or better footing.
Half buy. Cheaper weapons and light shields. Sometimes correct, often the worst of both worlds: enough spending to hurt the next round, not enough firepower to reliably win this one.
Force buy. Spending everything you have on a round you would normally save, because winning it now is worth more than being comfortable later. Correct when the scoreline means losing this round effectively ends the half, or when the enemy is also weak.
Save. Buying little or nothing, keeping credits so the following round is a genuine full buy.
A save only works if everyone saves
This is the single most common economic mistake, and it is not really an economic mistake. It is a communication one.
One player buying a rifle on a save round does two things, both bad. They spend credits the team was banking, and they usually die with that rifle, handing the enemy a free weapon. The round is still lost, and now the next one is worse too.
Say the call out loud before the buy phase ends. An agreed force is far better than half the team forcing and half the team saving.
Keeping your gun is worth a round
If you are going to lose a round anyway, the most valuable thing you can do is survive with your weapon.
A rifle carried into the next round is a rifle you do not have to buy, which often turns a forced half buy into a real one. This is why disengaging from a lost round is a skill rather than cowardice, and why chasing one last kill in a round that is already gone is usually a mistake that costs two rounds instead of one.
The same logic applies in reverse when you are winning: taking the fight that denies the enemy a safe exit is worth more than the kill itself.
Read their economy too
Your buy should respond to theirs.
After the enemy loses a big buy round, they are often forced or saving. That is the moment aggression is cheap, because you are likely taking a fight against weaker weapons.
After they win two rounds in a row, assume a full buy and plan accordingly. Walking into a full buy with a half buy and no plan is how a close game becomes a one-sided one.
The decision, not the arithmetic
Nobody climbs by memorising credit values. Patches change them, and the numbers were never the interesting part.
What transfers is the read: given this scoreline, this team's credits, and what the enemy just did, is this a round to spend or a round to bank?
That is the call Klymo drills, in the buy menu itself, with the reasoning shown once you have answered.