1. A Good Globe and a Current Atlas
If you want to study geography, you're going to need to make sure that 1) you have a globe and 2) that any atlas you are using is as up to date as possible. Many countries have divided and political borders have been redrawn over the years. Therefore, studying an atlas that was produced even just ten years ago will not produce the results you would like.
Choosing a globe is not an easy task. There are many different types of globes and each has a distinct use attached with it. When shopping for a globe, you will want to find one that is current, shows the lines of longitude and latitude, and is as detailed as possible. While gem-set globes are beautiful, they are not very useful. Make sure that when you're shopping for a globe, you're getting the most detailed globe you can afford. Globes will give you the most accurate depiction of where one place is in relationship to another, since any flat map is distorted.
Atlases are a bit easier to choose. Atlases will give you a much more detailed view of a region. For example, if you're reading about Mesopotamia in your world history class, you may turn to your globe and find the land between the two rivers on your globe, then look in your atlas to get a more detailed depiction. The best atlas for your study is the Atlas of the World produced annually by Oxford University Press. You may also wish to invest in The Atlas of World History, which will help you in your world history classes.