The Tanzania Tourist Board will send you some brochures upon request so it's worth contacting them in advance; their website, www.tanzaniatouristboard.com, is a good source of general information. For information about game parks, including accommodations and tariffs, visit the website for Tanzania National Parks at www.tanzaniaparks.com.
Planning a trip to Tanzania is a little more difficult than planning your average overseas vacation because it's not easy to pre-book your arrangements, prices often change without notice, and train and bus schedules can be unreliable. To minimize confusion, consider going through a reputable tour operator who can pre-arrange all your activities while in Tanzania and tailor a trip that suits what you want to do and see. There are countless operators; a good place to start is www.tatotz.org, the website for the Tanzania Association of Tour Operators.