来【lái】

来 can stand in for whatever verb the situation calls for. Its most common job is volunteering: 我来 means "I'll do it", 你来 means "your turn".

来 + verb: taking it on

Before another verb, 来 says the person is stepping in to do it. It doesn't mean coming anywhere.

Ordering and asking for more

来 + quantity + noun orders food or drink: "give me…". 再来 asks for another, or for something again.

Where it goes wrong

来 comes before the verb it stands for, not after it.

• × 我做来 → 我来做

A learner hearing 我来做饭 sometimes reads it as "I come to cook". The person is already there; 来 is the volunteering.