Read the manual for the glider; the spin characteristics were worked out by
a professional test pilot, and the best advice you can get will be in the
operating handbook.

Great advice, although with my Sisu 1a no such manual exists... that
said, it had a very well designed V tail that required no special
considerations for initiating or recovering from spins, and there were
no other indications in flight that would indicate it's unconventional
configuration. Spin recovery was quicker with the flaps retracted
though, so that too was a consideration, although probably not one
specific to V tails.

I personally enjoy spinning ships, and like to do what I call 'spot
spinning', meaning coming out on predetermined headings after a
predetermined number of revolutions... WEEE great fun!! Haven't got
into inverted spins yet though...

-Paul