how do you say phrases like, "you look good" and "you sound sick"

You look good is not such a good example of these type of sentences.
You look good is a different expression.
You look good. → Ou chèlbè, Ou anfòm, Ou anpenpan, Ou bòzò, etc...

But in general you would used "genlè" or "sanble" to translate such sentences.
genlè literally means to have the air of...
sanble literally means to seem to...

Examples:

You look / sound sick.
Ou genlè malad.

(Literally:  You have air sick)

You look mad.
Ou genlè fache.

(Literally:  You have air mad)

You sound scared.
Ou sanble pè.

(Literally:  You seem scared.)

He sounds sad.

Li genlè tris.

(Literally: He has air  sad)

They look ripe.

Yo sanble yo mi.

(literally: They seem they're ripe)

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