Rolling your eyes?!
Well, the main one I'd propose:
No attacking any player's starting-province for the first TWO turns, not just one.
It never happened to me, but I always thought it sad when someone signs up, possibly their first game, looks forward to the game, works out how to put orders in for one turn, ... and then gets RIPped early in Turn 2 before even their second set of orders take effect

Now, we can't give newbies a free pass, but if nobody can take anybody's start-prov for TWO turns, they'll at least GET two turns, and hopefully even be able to fire off one round of missiles before the attacks on Turn 3, at least a BIT of fun.
And they might get into new diplomacy after a bad start on Turn 1, since they'll still be around at least one more turn...
I worry that half our new arrivals will have SUCH a short game that they can't see why it's ever fun. Doubling their turns from one to two (plus missiles) might help a bit? Why not?