If scrying with crystal, make sure it is a clear quartz, a larger crystal is better. Choose one that 'calls' and appeals to you. It doesn't have to be your own personal crystal.
To view the crystal you can do one of several things:
The crystal should be at eye level, as you turn the crystal you will see many different things within it.
Look into the crystal and focus on the images within. Examine shapes until one 'calls' to you. Turn the crystal in different directions and look at the different shapes, images and messages. As you look at the shapes and images tune into, and listen to your thoughts.
Try interpreting the images, they may be about yourself, or events that have occurred near the crystal. Have trust in yourself as you will know what is best.
As with everything the more you practice the better you will become. If you don't see any images or shapes, then try another crystal, as the crystal you are using may not be tuned into your frequency.