I am working on double checking my intonation on scales,using a tuner to see if I can spot the trends where I go off. I also am practicing without the tuner and really working on trying to audiate as much of the scale as I can.
To this end, using a mirror or iPad camera to keep an eye on my left hand – watching for microcrawls, unneeded finger shifts, keeping 4 near position when I extend back for Bb or Eb.
Other than that, quiet summer. Outside of cello, have begun looking seriously into kayaking as a hobby.