Practice or practise?
The noun ‘practice’ is used as in the following examples:
The dental practice is within walking distance.
She has an accountancy practice in town.
I’ll put my plans into practice.
The orchestra is out of practice.
Practice makes perfect.
It’s good practice to look before you leap.
The verb ‘practise’ is used as in the following examples:
She practises the violin every day.
The tribe practises cannibalism.
She practises dentistry (in her dental practice).
And if you are very skilled at something, you are ‘practised’ at it. ‘Practised’ is an adjective.
The American way
No such nonsense goes on in the States: practice is used as a noun and a verb, and ‘practised’ is spelt ‘practiced’.