Lots and lots of tips on the giant thread, but if they get replicated here too, that doesn't matter, the important thing is that people see this and heed it.
Ive just said on the other thread, if you live in or are near the red warning area, charge up devices and have a plan on what you would do should you lose power for a day or more.
Use water sparingly.
Read this
www.nhs.uk/conditions/heat-exhaustion-heatstroke/
Check on vulnerable neighbours. Studies show that social isolation is one of the biggest factors in heat related deaths.
Don't plan to use public transport.
Schools should close (in my opinion)