Venice is without doubt one of the most beautiful and popular cities in the world and you'll find many bed and breakfast or hotels to stay. Of course you'll probably get your reservations online. You must be very careful, and check if the hotel/B&B site has proper pictures displaying the rooms conditions, a good description of services, and where exactly it is located, if is nearby the center or at least nearby a train/bus station.

That said, you won't have many problems finding good places to stay. Just be careful not to spend too much... unless, you really want to pass one night in those super-luxurious suites with a view on the "Laguna"!