"practise on" is correct and usable in written English.
It is most commonly used when talking about practicing a skill, such as "I need to practise on my guitar playing."
Otherwise, try to practise on like service, forehand, backhand, etc.
Next, the teacher demonstrates the skill using a student, a (simulated) patient or a model, after which students practise on models or one another.
("He must practise on melons," Iona says after Duckie unexpectedly plants one on her in Pretty In Pink) Sex is complicated.
"I lived in a little bubble in Covent Garden," she says, "and in the summer I'd only take one week off, then go back to the studio and practise on my own".
I told him to practise on me.
Phrase books are good, too – practise on the waiting staff.
"Derartu used to practise on the field here every day.
I'd say 95% of players will practise on Christmas Day.
Flirting tip? Practise on people you don't fancy.
I've got him taking English lessons and we practise on Skype.
At school, though, I'd practise on my friends, 'cause I could certainly be funnier than them.
