As and like

Use like before a noun, as in:

She's very like her mother.

Where a clause follows, you should use as or as if, e.g.

He's behaving as if he owns the place. ---- This sentence is a right one.
He’s behaving like he owns the place. ---- This sentence is a wrong one.

Or

You don't know him as I do. ---- This sentence is a right one.
You don’t know him like I do. ---- This sentence is a wrong one.

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"Nay! man is evidence against himself. Though he puts forth his excuses." Holy Qur'an (75:14-15)