It is always good to buy 2 sets of the same dart flights. When you ruin a flight you can just pull 1 flight out of your new pack. This way you extend the life of your flights by 3 times and are not playing with mix-matched flights. "Tear Drop" shaped flights are a good in-between size for the player that does not throw hard, but does not loft with a lot of arc.

Tear Drop Shaped Dart Flights