mind how you go
1. Be careful. Primarily heard in UK. Mind how you go with that stack of plates, love. I don't want them to come crashing down on top of you!
2. Used as a conventional parting phrase. Primarily heard in UK. Thank you for coming to visit. Mind how you go!
ˌmind how you ˈgo
(informal)
1 used to tell somebody to be careful: Mind how you go with that knife — it’s very sharp!
2 used when saying goodbye to somebody: Goodbye then! Mind how you go!