What's the best way to get a good price on a hotel room?

I don’t travel much, and I used to just call the hotel, make the reservations, and take the price offered.

Now there’s all these services like Expedia and the rest. I have no experience with them at all, and I have trouble trusting these entities that exist only online.

Who do you use? and how do you navigate among them?

I’m looking at a Cambridge destination in August.

Thank you.