Look outside, for starters. The situationally aware pilot will track his or her fuel consumption independently of the gauges. Remember that endurance counts here, not range. Topping the tanks is always a good idea, unless weight forces you to take off with less than full fuel. Know your fuel system.
Fuel starvation landing with a quiet engine while there is still fuel in the airplane still happens.
And don t overlook your fuel state if your flight is interrupted by the need to resolve an anomaly. Land and refuel before your supply gets critically low, even if you are almost home. Continual worry about reserves is a sign that you need to stop.