If you are using a travel guide, it will contain hotel recommendations. Most of them have reviews, including prices or least priced categories for each. Many will be able to book online.
Some of the smaller, independently owned hotels are still making a reservation. You can mostly reply via email, but some are a little old and only by phone. If so, do not let the idea of calling internationally and talking to someone that English does not have to be their first language, to intimidate you. They are entrepreneurs who feed on providing rooms to tourists who guess what they probably do not speak in their native language. Everybody speaks English enough to book!
Check out your travel plan and start booking these hotels for each location. In general, you wish to book at least 2-3 months before making sure that you are able to get exactly the hotel you want. If you are traveling during a peak season, you may want to start a bit earlier. Most hotels require a credit card reservation, but most allow you to pay in cash on arrival.
When booking these hotels, please enter the contact details (hotel name, address, phone number) and save the records. There is also an amazing website called Tripit, which has a tool for creating itineraries that lets you manually enter this information, or even has a function that you can pass it by confirmation email (for hotels and even airline information) and actually for will do you.
For my hotel choices, I'm going to the middle of the way. I can not afford to stay in five-star hotels, but I do not want to bother with uncomfortable circumstances such as the crowded Youth Hostel. I will love to have the best of both worlds: to experience the land, the people and the culture in which I dived without staying in "noisy" accommodation. I leaned forward to small, independently owned hotels, near the city center, but I protected them from areas that were poisoned by tourists.
Moreover, most of these self owned small hotels run by their own owners, who are always more than happy to help guests. They are one of the best travel advisors you will meet when you are there. They can tell you where the best places to eat, the easiest ways to move around in the city, even help you book museum reservations and excursions.