The objective in flat scissors is the same as in all overshoot tactics. You try
to reduce your FORWARD movement as much as possible to force the opponent out front.
The basic maneuver looks like a zig zag flight path. You make a (hard) break turn in one direction, then you change direction again.Use rudder to help your roll (also adds a little sideslip and makes you a more difficult target) and drop flaps if you need to (speed!).
As you can well imagine, if you do this in a regular rythm, the opponent just has to *anticipate* your next position and shoot. So, *never* ever get a rythm going. Make it irregular. Rolex once told me to count down, randomly, from a number between 1 and 5 back to 0 (direction change) - that worked for me.
Even *better* is watching your opponent. Hell probably be following your turn a split second later. As soon as you see him getting his wings lined up with yours (=shooting position!) - change direction. By staying "out of phase" like this youll make it a lot more difficult for him to hit you.
Speed: Well, id would say as fast as possible but as slow as possible to make the guy overshoot. Now i know that probably isnt very helpful - in the arena, youll have to fly the maneuver at whichever speed you get caught at. How *slow* you get while scissoring depends on how tight you have to pull your turns to make it work. If you have an enemy that has lots of escess E (is a lot faster then you), you will just have to pull a few lazy sweeps at full throttle and hell be past you. If the E states and planes are more even matched, you might have to go off throttle and maybe even drop flaps when starting your turns, slowing down to stall speeds.
Extensive use of flaps/gears. Yes, that *might* help - ive used it in the past. But you have to be aware of the consequences and carefully pick the situations in which to do it. Doing all that will slow you down heavily .Yes, i know, thats intended, BUT: Youll be left, low, slow - no E - and an easy kill for others around or the opponent your trying to make overshoot if the scissors fail to work.
By flying zig zag, you reduce your forward moving speed far below minimum flying speed. That, as well as the fact that the opponent will follow you in lead turns (hes trying to shoot you!) will play for the overshoot.
is a film of Schutt scissoring a Spit in his 109 that shows what happens. Best watch that one in External View with Trails, Icons and Recorded Views checked. Notice how Schutt keeps watching the Spit and adjusts his turns. The Spit overshoots fast, only getting a few pings... as soon as hes out front he pays the price.
The film also demonstrates the dangers of a scissor. You get yourself usually low and always SLOW. That leaves you open for attacks, since you dont have many options. In this case the a6m took advantage of Schutts position.
Edit: If you have enough Advil at home and want a more detailed explanation on scissoring - THIS is a very good article on scissoring. It helped me understand a lot about the inner workings of 1 vs 1 fighting.