I have just finished reading a great book on Acting dating from about 50 years ago. Amongst the 'tips' were several exercises that actors can do alone to maintain their sharp edge for upcoming auditions and bookings.
I'm interested to see what actors, here, do to 'keep their hand in' bearing in mind the restrictions of our craft.
Mmm... not enough? LOL
I run a taping service for actor auditions, so cold-reading 1-pagers up to 15-page auditions 5 days a week for over 12 years has served me well. I find myself getting off book by the actor's 3rd take, and I'm also in tune with the 20-30 tv/film projects shooting in Atlanta, GA, USA at any given moment.
For me it's thinking of it holistically - so doing breath work, tapping into my emotions and the things that trigger certain emotions i.e. perfume, food, music. Then when I experience those emotions, I ask myself why I'm feeling that way. Just little things to make me more aware and in tune.