What makes the best survivors

Generally as a solo player you need to have a good mental image of your surroundings, know the nearest pallets, vaults etc. When working on gens you need your route planned for when the killer interrupts

Knowing when and when not to drop pallet's is a big factor. If the killer is going to lunge desperately to try get a hit when you drop the pallet, just don't drop it, loop it again. They should miss, chances are they're too far away to reach the other side of the pallet so just run through it (if they don't lunge and you don't drop the pallet you're getting hit, take note of each killers behavior at pallet's if they're respecting them too much keep looping it)

All the mindgame stuff will come with experience. Playing killer at higher ranks help's too because you get an idea of the general survivor tactics (t-bags and flashlights basically) and you will remember the stuff that works

While there's obviously more "obvious" aspects like knowing how to run different structures optimally as well as backup plans if the killer knows how to deny them the optimal route (like killers not giving them the optimal path on TL walls or the pig tree), a lot of it comes down to quick and correct prioritization.

Know when to heal and when to not, know when to run and when to try to avoid detectionm, know what gens to do first and which to avoid, know if they can make another round in the loop they're in or if they should drop the pallet - that sort of thing. As well as obviously not instantly dropping everything to race everyone else for every unhook.

A dead one.