The following are very common ways in Italian of approaching strangers when asking for directions or information:
For directions to somewhere:
1. Scusi, per andare nel centro storico?
Excuse me, how do I get to the centro storico?
2. Scusi, sto cercando piazza San Michele
Excuse me, I'm looking for piazza San Michele
3. Scusi, si va sempre dritto per il centro?
Excuse me, is it straight on for the center?
4. Scusi, mi sono perso. Dov'è via Fillungo?
Excuse me I'm lost. Where's via Fillungo?
For information, availability etc or in the supermarket, on a train etc
1. Scusi, dove si trova la stazione? Da quale binario parte il treno per Lucca?
Excuse me, where can I find the railway station? What platform is the Lucca train?
2. Scusi, c'è una farmacia qui vicino?
Excuse me, is there a pharmacy near here?
3. Scusi, mi sa dire dov'è il supermercato?
Excuse me, can you tell me where the supermarket is?
4. Mi dà una busta?
Can you give me a bag? (asking for a plastic bag at the supermarket checkout)
5. Scusi, mi può dire se c'è un autobus che va al supermercato?
Excuse me, can you tell me if there's a bus that goes to the supermarket?
6. Scusi, posso parcheggiare la macchina qui? Bisogna pagare?
Excuse me, can I park my car here? Do you have to pay?
7. Scusi, è libero questo posto?
Excuse me, is this seat taken?
8. Posso?
May I? (eg. when you want to take a chair from another table outside a cafe, though this is commonly used also among people you know when reaching for something and asking permission, just as it's used in English)
9. Permesso
Excuse me ( eg. when you're trying to get through a crowd of people)