Good job. Well done.
When I want to praise someone, I know those sentences:
Good job.
Well done.
Good for you.
You killed it.
You nailed it.
You smashed it.
Any else I could say? Can I say it to my teachers or my parents?

Question

Good job. Well done.
When I want to praise someone, I know those sentences: 
Good job. 
Well done. 
Good for you. 
You killed it. 
You nailed it. 
You smashed it. 
Any else I could say? Can I say it to my teachers or  my parents?

Answer

Yes, you got it. !

Answer

Some other common ones:

Nice work

Good work

Great work

Great job

None of them are offensive, but 'you killed/nailed/smashed it' is quite colloquial and is more common among friends than with parents/teachers.