Once again, everything depends on your final destination. The most convenient option is to book a transfer.
If you’re an experienced traveler and want to get to know the country using public transport, you’ll first need to take a train to Châtillon/Saint-Vincent, and from there — a bus to Breuil-Cervinia Valtournenche. You can find a detailed train schedule on this website: www.trenitalia.it.
An alternative way to get to Breuil-Cervinia is by renting a car. If you choose this option, follow the A5 highway from Turin to Aosta and exit at Châtillon/Saint-Vincent, then drive approximately 28 km toward Cervinia.