Pilots need to be familiar of the situation they are departing into, be prepared for the anticipated conditions, have a good and realistic plan to get to the destination airport, and have a plan of action to deal with the unexpected. The following two regulations specifically state these requirements in more definite terms and make them a legal requirement.
The preflight action regulation states that pilots must become familiar with all information concerning the flight. If there is some piece of information that affects your flight and that information is available to you, you need to be aware of it. At a minimum, pilots must make sure they know how much runway they will need and how much runway they have. If the flight will leave the local airport area, then the pilot must also, at a minimum, check weather reports and forecasts, know fuel requirements for the flight, and have an alternative plan of action if the flight cannot be completed. You must also anticipate traffic delays you might encounter in flight, such as traveling to an airport for a busy airshow, for example.
Minimum fuel required is enough fuel to fly to the first point of intended landing and then fly at normal cruising speed for 30 minutes during the daytime or 45 minutes at night. It is the pilot's responsibility to factor in wind and other weather conditions.
ยง 91.103 Preflight action.