learning acro, full stall... what is the next? Spin/Negative?

Hey guys!

I want to learn acro and need your advise!

I´ve done some fullstalls, sats and realy good wingovers, but what is the next step after controlled full stalls?
Tailslide? Spin/Negativ? .........or Infinity Tumbling?=)

I am flying a skyline buzzard, what would you prefer as next step?

Greets
Josi