Expression

I would say, "work the phone lines," "man the booth," and "work at the checkout."

2) If someone asks :Do you still have any perfume?

What could I answer/(OR RESPOND??) : "I've used up all of my bottles" or "No, all of mine ran out"? What would you say?

I would say either! Or simply "I have none left, sorry."

3) I don't seem to be able to use the expression get dirty properly in English. As a consequence of that, I've been trying to find a appropriate word to use.

I thought I could use "get + the name of the thing", but someone said it would sound awkward

I'm unsure what you're asking here. Sorry.

Rather than saying "My dog got the floor of my room dirty with its mud-covered paws", I would say "My dog got mud on my floor of my room with its dirty paws"..... But a person said both are odd. What could I say instead?

I'd rather say, "My dog tracked mud all over my floor with its paws!" or simply, "My dog tracked mud on my/the floor."

I hope this helped!