NWKRAFT is a mnemonic used by general aviation pilots to remember what information and actions are needed while doing preflight planning. Such planning is required and described in the US aviation regulations in 14 CFR 91.103. It is generally pronounced "En Doubleyou Craft." The acronym is is follows.
N - NOTAMs. This includes all official (and unofficial) notifications that might affect your flight. Be sure you have read an understood each NOTAM presented to you based on your departure, destination, intermediate and alternate airports, as well as any others presented for your general region of flight, and noted down any that you determine apply to your flight.
W - Weather. Covers the whole range of weather awareness and planning. Ideally, you should have been following the weather for a day or more in advance of your flight to get a sense of any trends and changes, over and above determining if the forecast is favorable for your planned flight given your equipment, plans and most importantly your personal skills, currency and comfort.
K - Known ATC Delays. A weak acronymic, yes, but what can you do. Be sure you know if there are any published delays at any of your airports or into and out of any controlled airspaces you intend to traverse; this may have an impact on your fuel planning (or your bathroom stop planning!)
R - Runway lengths. Fairly self-explanatory - be sure you know the lengths of all available runways at your relevant airports for your route.
A - Alternates available. Have information on each airport you consider an alternate destination. If your flight is longer than an hour or so, you should have 'divert' alternates along your route in case of trouble, weather changes, or passenger discomfort (or bathroom breaks, again!)
F - Fuel requirements. Based on your aircraft's GPH consumption rates, your planned cruising altitudes, and the relevant wind, be sure you have enough fuel on board to reach your planned destination (or any stops) with adequate reserve aboard to meet your personal minimums, which should be higher than the regulatory minimums. In the U.S., that's 30 minutes of reserve for daytime VFR and 45 for night VFR (14 CFR 91.151), or 45 minutes beyond the designated alternate airport for IFR (14 CFR 91.167).
T - Takeoff and Landing Distances. Make sure you know the estimated takeoff and landing distance requirements for your aircraft and loading at each stop and alternate airport. Don't forget density altitude as well as any NOTAMed obstacle clearance requirements!
And there you have it - NWKRAFT. Use it wisely, pilot.