I don't want to give offense, but I *really* don't want anyone taking this post for "the truth":
"DO NOT fly with anyone who has 'just gotten their license'".
Nope. Don't fly with the 1000 hour pilot who hasn't flown in years. The pilot who has "just gotten their license" has just passed a reasonably rigorous practical test by the FAA or their agent. Yes, they're newly fleged and they're still learning a great deal, but the highest accident rate is (I think) around the 500 hour mark.
"DO NOT fly with anyone who is not instrument flight rated if there is ANY possibility of a storm or nightfall during your flight."
Visibility is important. Scattered showers can often be seen miles away and avoided visually. A very hazy day (say, 4 miles visibility) is legal for "visual" rules but much more dangerous than the above mentioned storms.
"That's waht killed JFK Jr and his passengers - he tried to fly at night when he was not qualified."
I think the NTSB report said that he effectively flew into instrument conditions. Yes, night didn't help. Neither did the overcast, the 10 mile visibility, or the fact that he was flying over water (they don't tend to put lights on the water).
"If you go up with someone who makes you at all uneasy with their attitude, require them to land immediately"
Excellent advice.
"At the least, you can ask the pilot how many hours he/she has in mountain/desert/whatever flying (1000 hours would be a good start)"
1000 hours in a given specialty is a whole lot of hours. You probably don't need near that many. This will also probably keep you neatly on the ground.\
"ask them to request 'flight following' from the airport. This is a service where they check in with the airport/control every 15 minutes, giving their heading and location"
Nope. The mis-named "flight following" just means that the radar guys will keep an eye on you if they aren't too busy and let you know about other airplanes if they find it convenient. The service the poster mentioned can be had in a few places, notably if you're crossing the Great Lakes or Long Island Sound.
Let me give you a few more tidbits
Most accidents are caused by "unplanned flight into instrument conditions". These are far to often fatal.
Way too many are caused by simply running out of gas. These are often survivable.
Most mid-air collisions ocurr in good weather in the day time. No storms, no darkness, just someone not looking out the window.
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Dewey