GRAMMAR POLICE....Please check this!

[Comfysock]

Is it...

A. Sign up to my VIP list
B. Sign-up to my VIP list

A.

Sign up - a verb
Sign-up - a noun.

So A

It's A.

Are you in need of a verb or a noun in this instance?

@Jellyx is correct

A verb...Im asking them to 'do something'

So if you're asking them to do something, that's a very - so A.
You could use B if you said, here is the sign-up sheet for the VIP list.