Drums:
Usually drum kits in studios are generic. It’s better that drummers bring their own (at least snare and cymbals), so they be comfortable when playing or choosing what suits the music better. Check all the hardware for squeaky or rattling noises. Replace your drum heads.Triple-check you pack all you need.
Guitars and bass:
Set your instruments up properly to eliminate any fret buzz. Change the strings but play them for at least a couple of days, so the instrument sounds brighter/clearer but stays in tune longer. Test your amps and pedal effects, and listen for worn out valves, noisy fans or other undesirable sounds (if you need to, have them repaired).
Vocals:
Even though vocalists don’t have any equipment, they should still treat their vocal cords as such. Be certain that they are in good condition. If you have a sore throat or have lost your voice is better to reschedule a recording session with sometime in advance than loose time and money. Take good care of them and warm up properly!
Other instruments: