No tricks at all---
This is a maneuver which is very dependent on the aircraft design.
Basically , you want the model to pitch (up/down) whilst starting to roll.
The shape of the wing planform can really affect this .
The shape of the leading edge - maybe - but don't bet on it .
The plane needs enough speed to be stable - snaps at an idle work on some really light stuf but for most - a stable speed is necessary.
So -- basic upright spin from level flight:
apply hard elevator input -then aileron and rudder .
Release elevator -then rudder and lastly, aileron.
On some designs a good snap can be from full input of all three and releasing all three at once --you should be so lucky.
But basically , the model must pitch ( stall the wing ) then autorotate till it restabilizes.
A light model is always better .
Why ? The return to stable flight is more predictable .
Any snap , which is NOT started from level flight takes less (typically) rudder and elevator
to continue - a snap started vertically (up or down ) will stall the wing much faster -simply because it is loaded far less in verical attitude than in level flight -
So to recap; level flight snaps require more inputs than vertical -with all in between starting angles some degree less.
Here is more good news--
The more deeply you stall the model -- the more speed you loose and the more chance there is to over rotate from the inertia in the rotation plus the lessened response of the flying surfaces to the direction of flight.
A snap can be done at any speed - so experiment - but start with and try for a snap form a moderate speed
don't "lead the snap BUT if you can think of it -- CHEAT IN a bitte of opposite rudder before the snap is commenced .
Why?
to make the apparant snap stay exactly on heading
A true snap will displace -a little or a lot - the heading.
There are my secrets -
FWIW