My memory is slightly hazy, but in the RAF Bulldog it was absolutely essential that the fuel balance limits were carefully observed. NEVER spin one with suspect gauging!
Observe the Centre of Mass limits meticulously.
After HASELLs and a 360 deg clearing turn, decelerate in straight flight with idle power and ensure the aircraft is in trim at 70 kts, do not trim below this speed. At 60 kts, briskly apply full aft control column AND simultaneously apply full rudder, ensuring that ailerons are held neutral. MAINTAIN THIS FULL PRO-SPIN CONTROL POSITION!!
There will be some oscillatory activity as the aerodynamic and inertial forces reach a balanced state and the stable spin is achieved. During this phase, MAINTAIN FULL-PRO SPIN CONTROL. If the control column position is relaxed slightly, the ac WILL enter a high-rotational regime with much greater loss of height and longer recovery time.....
To recover, keeping full pro-spin control applied, check height (if you have the luxury of a 'chute), then check throttle closed, ailerons neutral and direction of turn. Apply FULL anti-spin rudder and using BOTH hands on the control column, at the same time firmly move the control column CENTRALLY FORWARD UNTIL THE SPIN STOPS. Do NOT stop this forward movement until it does so! It is easiest to say out loud "Spinning Left, recovering. Full-right-rudder-and-control-column-centrally-forward-until-the-spin-stops" because that will give you roughly the right cadence for the recovery. Then centralise the rudder, level wings, ease out of the dive and select the S&L attitude, carefully opening the throttle until S&L flight is regained. There will be a slight bunting sensation and increased rotation as the spin is 'broken' but that'll indicate that recovery is becoming effective.
Not a particularly pleasant manoeuvre, but not dangerous if the CORRECT technique is used. In the RAF we used to practise the fully-developed spin from manoeuvre which could result in a spin with aileron and/or full power applied. It was then VITAL to do the 'throttle closed, ailerons neutral, full pro-spin applied check' as soon as the fully-developed spin was identified!
This is NOT a substitute for proper training, nor a replacement for handling advice in the POH. But it may help.