It's not clear to me how to go about this.
Use a new address for EVERY payment of Bitcoins that you receive.
Say I want to meet with someone that sells an item or service, how do I pay this person without revealing your funds?
Use coin control. Spend an output that is very close in value to what you are sending.
These are good, but they are not enough to ensure total privacy.
Ideally, you would want to send the transaction in a payjoin, which (and I'm sure you already know this) is just two transactions smashed together.
So there's going to be two inputs, and then there will also be I up to 4 inputs if the amount is not exact, otherwise as low as two outputs.
A payjoin is not easy to coordinate manually so this will most likely be orchestrated by the platform that you are trading on such as Bisq.