Starting point. Load the ForeFlight NavLog and the weather briefing:
they provide route, waypoints, distances and times, then wind, QNH, temperature, METAR, TAF and NOTAM.
Once both have been read, proceed to the flight plan.
NavLog ForeFlight
Click or drag the NavLog exported from ForeFlight (PDF or text)
Airports, route and distance are taken from here. Speeds and fuel flows are not:
those remain the POH figures, which take precedence.
Weather Briefing
Click or drag the WX & NOTAM briefing PDF
METAR, SPECI, TAF and NOTAM are sorted onto DEP, ARR and ALTN, and from there
feed wind, QNH and temperature into the performance calculation.
Sorting uses the ICAO codes read from the NavLog: load it first if you can.