Jak to powiedzieć po polsku: "What do you recommend I do (in Wrocław)?"
What are the most common ways to ask for advice in Polish?

In English, we would ask:
"(When I visit Wrocław,) what should I (do/see/buy/etc.)?"
"What do you recommend?"

Question

Jak to powiedzieć po polsku: "What do you recommend I do (in Wrocław)?"
What are the most common ways to ask for advice in Polish?

In English, we would ask:
"(When I visit Wrocław,) what should I (do/see/buy/etc.)?"
"What do you recommend?"

Answer

Co można robić we Wrocławiu? - What can one do in Wrocław? 
Co można kupić we Wrocławiu? - What can one buy in Wrocław?
Co można zobaczyć we Wrocławiu? - What can one see in Wrocław?
Co można zjesć we Wrocławiu? - What can one eat in Wrocław?

(można - it is possible; one can (used to express possiblity)

Co warto zobaczyć we Wrocławiu?  - What is worth seeing in Wrocław?
Co warto kupić we Wrocłąwiu? - What is worth buying in Wrocław?

Answer

Co polecasz zobaczyć we Wrocławiu?
What do you recommend to see in Wrocław?

Co mogę ciekawego robić we Wrocławiu?
What interesting things can I do in Wrocław? (I'm not sure if this is correct in English but I hope you understand)