Erasers are the sort of thing to have with the idea that you will use them only sparingly. Each time you use an eraser, you risk smearing the drawing or damaging the paper.
The first eraser you get should be a kneaded eraser. These soft, putty-like erasers are very gentle to the paper's surface and leave few, if any, crumbs. To erase, first try pressing the eraser to the paper's surface; this is less damaging to the paper than rubbing the eraser back and forth.
Use a white vinyl eraser to remove hard-to-erase pencil lines. White vinyl erasers are more abrasive than kneaded erasers but will not stain the paper, as some colored erasers often do. White vinyl erasers leave behind strings rather than crumbs, making cleanup easy.
Made of thin metal, an erasing shield masks the areas that are not to be erased. To use it, with one hand firmly hold the shield down over the area not to be disturbed and, with your other hand, carefully erase over top of the shield.
Never use the eraser at the end of a pencil. It may smear pencil lines and stain the paper.