Primary answer: Use the spin recovery technique which is described in
the AFM.

Secondary answer: All certificated modern gliders will recover with the
"standad procedure", it's a requirement for certification.

That said: Eric Müller was a, no, probably *the* spin expert. He
described the ins and outs of spins in detail in his book "flight
unlimited". According to him, most "conventional" tail designs recover
best when you keep holding the stick back until the rotation stops,
because pushing it forward will blank the rudder. With T-tails it's
exactly the other way: Pushing the stick generates more airflow on the
rudder to stop the rotation. V-Tails are a story by themselves. There
has been at least one fatal accident with a salto which spun into the
ground. Eric was the accident investigator for this case and examined
the spin behaviour of another salto. He found that the salto would only
recover with the stick pushed *fully* forward.

But again, this is the theory, in practice, do whatever the AFM recommends.