My favorite plane sleeping solution is to tie the arms of a long-sleeved T-shirt behind the headrest such that the body of the shirt hangs in front of your face and the shirt keeps your head from moving. No more nodding and waking yourself up! And bonus darkness!
The sleeves end up sitting basically at the top of the back of the seat, so they're not in the way. I guess this wouldn't work if you're significantly taller than an airplane seat, like if your whole head is above the top of the back of the seat.
I bring a scarf and knot it under my chin (the normal way: fold in half, wrap around neck, put two loose ends through the loop; but tighter than normal, so the lump sits under the chin just to one side). Provides enough support that my head stays back and doesn't look weird.