Choosing the Best Hair Spray for Your Style:

While some sprays are recommended for specific types of hair, the biggest consideration you need to make when choosing one is whether it will work for your style that day. Many users keep a number of different sprays on hand so they can choose which one works best with different looks. For example, if you plan on being outdoors on a windy day, you may want to consider a stronger hold than normal. If your style only needs hold in a few small places, a non-aerosol product may be best. For a more natural, casual look, a flexible hold spray is a good choice, while elaborate  may require far stronger holds.
How to Use Hair Spray:

Using a spray properly takes more than just holding it near your hair and pressing a button. For the best looking style, you must consider exactly why you are using the spray and how to achieve fabulous results. In general, the spray can or bottle should be held upright 8-12 inches from the hair (aerosol sprays should be held further away than non-aerosol products). Always remember that most spray is inflammable and should never be directed at a heating tool such as a curling iron, hot hair spray or straightener. A single loose connection or spark could have disastrous and dangerous results. Furthermore, avoid getting spray in your eyes to avoid inflammation.

Reference Source: http://hair.lovetoknow.com/Hair_Spray