To get the very best pictures of El Capitan, you really need to pay attention to the quality of the light and the weather. Morning or afternoon light work best depending on your location, and having clouds makes the picture more interesting than clear blue skies.
When photographing El Capitan from the various vista points, you'll be using lenses from as wide as 14mm to as long as 200mm. There are several filters you can use, and of course your tripod and cable release yield the best results.
Highlighted below are the lenses that are most optimal to use when photographing from the various locations.
For best results, use a wide-angle lens in the 20-28mm range. This range allows you to use a small object in the foreground while still capturing the full height of El Capitan.
From this location it is recommended that you use a very wide-angle lens in the 14-24mm range, which is necessary to capture both the Merced River and El Capitan. In fact, you're probably going to need to turn your camera vertically to capture all of it.