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.
There will always be problems when dealing with fiat interfaces. I think the best possible thing to do would be to move to a jurisdiction that does not treat Bitcoin users as criminals by default. Unfortunately it is what it is. Which would be such jurisdiction? Im not sure, beside maybe Salvador, which im not into.
At the end of the day, what will bring the most privacy is an incentive for users to never leave the Bitcoin circuit. I think once governments ban cash, people will have an incentive to stay in Bitcoin and make payments, assuming LN manages to deliver an user friendly solution, and assuming there's enough privacy there to do so.
You will still require jurisdictions that are friendly to you to convert Bitcoin into any relevant tangible goods such as real state or diversifying in funds or stocks tho.