Meditation helps a lot, as does the Energy Points Chart from my post about fatigue which helps me plan my days and not overload myself.
Apart from that, getting the sleep I need (12-13 hours a day) does help as well!
My Doctors at UW/Harborview assure me that this will get better, and for my range and severity of symptoms they predict by June 2023 I should see an improvement. Learning to accept what I'm faced with has been a big part of the therapy group that I've been a part of.
The Mayo Clinic's website has a good description of Brain Fog in Long Covid here.