Scissors is a defensive move that is designed to generate angles for you and force an attacker into defensive flying.
Most guys I've seen try scissors (especially La-7 and 190 and 109) do it too rapidly. They make small rapid scissors that don't generate any angles. All they do is slow themselves down and make a hard target with maneuver warps. It works for them sometimes but usually I just throttle back and wait for them to make a mistake. Then I fill them full of lead.
With a real scissors you are trying to generate angles AND make the other guy overshoot. And you have to look back at him to do it effectively.
Flat scissors is good if you don't have any altitude to work with and you have a plane with a great roll rate. You start a break turn (pull to edge of blackout or stall, whichever comes first), then look back. When you see the bandit start rolling to match your bank angle, reverse your turn. Pull to the edge of blackout, wait for him to start rolling again, then reverse again. Repeat until he flies in front of you or stops following your reversals.
Since your turns are banked almost 90 degrees, you can roll either way to reverse. It takes about the same time to go from a 90 degree left bank to a 90 degree right bank whether you roll left or right. If you mix it up occasionally it can confuse the bandit. Use rudder to speed up your roll if your plane doesn't roll so well.
If the bandit is flying faster or can't pull as many G he will eventually pass in front of you. He might also collide with you, beware of this.
The rolling scissors is a better move if you have some altitude to work with and maybe your plane doesn't roll so great. It is just a scissors where you are always pulling G, and you generally roll in one direction. You break one way as in the flat scissors, but to make your reversal, you keep pulling and rolling in the direction of your break. You roll and pull, varying your G a little to confuse him but not varying roll rate too much.
You end up doing a big barrel roll - your path through the sky looks like a corkscrew. If your opponent is going a lot faster or can't pull as much G he will make a corkscrew of larger diameter and cover more horizontal distance and end up in front of you. Or if he is not faster but does not follow your maneuver and flies straight, you will cover less ground because you are flying a longer path, and he still ends up in front of you. Then you can zap him.
[ 12-08-2001: Message edited by: funkedup ]