01.
Coming in with a stuffed stomach and getting massaged soon afterwards can actually get painful. Nothing more than a small snack should precede your pleasure.
02.
Likewise, drinking too much before will most likely result in an urge to go to the toilet during the procedure, which will disrupt its course significantly. On the other hand, you should replenish those fluids after your massage is over, since your body will be in a state of light “overdrive”, and will be needed to stay hydrated.
03.
As for alcohol, it is fairly obvious. Not only does it decrease your sensibility and distorts your perception, but it also dehydrates you, which is the last thing you need, considering the rubdown itself is quite demanding on your organism.