Decide which region(s) or cities you want to visit and when
Apparently Italy has it all! Magnificent art and architecture, history, anthropology, food and wine, ocean resorts and islands, small villages and large cities, farmland mountains and forests... spend time browsing books on Italy to decide where you want to go. For us, it was three things: resorts by the sea, a wide swath of Tuscan villages and countryside, and the Venetian lagoons.
I started 'designing' my weeks in Tuscany by studying aerial photographs of the region in a beautiful book of photographs called
Flying High Tuscany by Antonio Attini. I flagged pages and started planning from there. Venice would be easier and more contained.
Browse travel books and maps
I went into a Barnes and Noble book store one weekday morning and Borders Books one Sunday morning, and took a stack of Italy guidebooks to a comfy chair (about 6-10 books each time) to browse through before deciding which ones to buy. I also looked at five or six large, detailed road maps of Italy before choosing one, because I planned on driving through Tuscany over 10 days and then to Venice, where the car would be parked.
Look through guided tour-books, even if you want to go it alone
A travel agent gave me this sage advice (and an armful of tour-books on Italy). Her thought was: look at the itineraries and hotels that are featured in these packages. Tour operators do the planning, footwork and price deals FOR YOU. Plus they know the sights, signs, language and customs. Even if you're inclined NOT to use a tour operator, at least see where they're going and staying.
Get the Guide to Italian Tourism "ITALY NOW" & other (free) info
The Italian Government Tourist Board has free printable maps, festival events, climate, and a 64-page book they will mail to you. Visit the site in resources below.
Price shop and consider travel insurance
Hotel and airfare prices are worth shopping on-line. Check orbitz, expedia, priceline, travelocity, and others before committing. If you're a member of AAA or Costco or Sam's Club, check their travel package prices, too.