Be like Mike, or do as he does
To emulate someone, you may want to be like him or do as she does.
The word "like" is considered a preposition followed by a noun or pronoun (like Mike; like your brother).
The word "as" is a conjunction that begins a new subordinate clause (as Mary says; as the instructor explained). Therefore, action (a verb) follows "as."
In informal English, "like" may be used as a conjunction meaning "as"; but in formal English, "like" is followed only by a noun or pronoun, never a verb. For instance:
Jane is a pianist like the master. (noun)
Jane plays the piano as the master does. (verb)
Sometimes "like" is substituted for phrases such as "as if" or "as though":
He looked like he had been in a fight.
Mary sounded like she had been crying.
"Like" is not a conjunction; use instead:
He looked as if he had been in a fight.
Mary sounded as though she had been crying.
— Sandi Ekberg taught high school English in Medford for 30 years, with a special interest in vocabulary, grammar and usage. If you have grammar questions you would like answered, email her at firstname.lastname@example.org