I know a lot of people already do this to some extent but the trick is do it every raid and dont stop.
Play as if you are completely immersed in the raid. Act as if you die in raid, you die in real life and play accordingly.
In the end tarkov is about not dying, if you dont die you dont need to buy another set of gear, you dont need to replace everything and best of all, you keep what you found in raid.
So here are my tips.
Do not take "50/50 risks", "If I push this I will probably die, but what if…."
Just not smart to take risks, just think about outcomes and how likely it is that you will die.
Never repeek an angle unless you are confident.
In tarkov you should never take direct gunfights unless you are playing labs or factory.
The best way to kill players and not die is peeking while not being seen and flanking or ambushing is your best bet.
Never peek somebody that knows your current position, of course there are scenarios where this will benefit you but 99% of the time, repeeking is a 50/50.
I have a few more tips but Il make a part if peopel want, nobody will probably see this but if you do just stick to the first tip, become your pmc and you will live much more.