First time couchsurfing – any tips?

I am heading to Porto, Portugal in a week. I already have a couch to sleep on, but in terms of meeting new people, getting around the city, what to prepare for – I need your tips. Maybe some advanced couchsurfers have any specific advice from their experience?
I’m also looking for some recommendations for mobile data. I saw a new launch from Nordvpn called Saily, and I am happy with their products, so I think I will go with that – the prices and plans look very good! Anyone used it already?