Always bring your own gear and use it. You know how it works and how
to use it. If you haven't played through a leslie before then don't
do it in the studio. The studio shouldn't be considered a practice
room.
Practice practice. Know what the arrangements of the tunes will be
before you get to the studio. Get you solos in orders and practice
them before you get to the studio. It's easier to bring fire to a
recording when you know exactly what you are doing.
With my CD the producer didn't like my solos (Eff him!!) so he
directed to play what he thought was good. Dumb idea. Do what you
do and play what you play. My next CD will make everybody's head
explode because I will do what I do best and that's make make
people's head explode.
Studio time is expensive so don't waste it by doing the work you
could have done before you got there.