Avoid overheating by using extension cords of the proper size for the load they will carry.
Use an extension cord as short as practical.
Regularly check cords for damage, never repair by splicing, discard old or worn cords. Cords should never be placed under rugs or covered, this may cause overheating.
Do not roll or loop cords, this may also cause overheating.
Avoid using "octopus plugs" which allow many cords to be plugged into a single receptacle.