So don't start burning leaves or trash during a red flag warning. It's also a good idea to wet down shrubs and such near a house, if there might be any chance of fire.
Also, don't shoot any fireworks or firecrackers. Sparks from these incendiaries can start grass fires easily. And if you mow your lawn, keep an eye out for your mower sparking and starting a fire. Keep the garden hose nearby so nothing gets out of hand. Same goes for using a chainsaw or any kind of equipment that could cause a spark.
A red flag warning should be taken seriously by those doing any kind of outside work.