To Change the Color of Flame:

For Candles: add the chemicals to the wax, or soak the wicks in a solution of  the chemicals using the "recipes" below

To Add to a Fire: Put three level spoons of the chemical into a paper cup; fill 1/2 full with water and stir. Soak several small chips of wood in this solution overnight. The next day, remove the chips with tweezers and lay on newspaper to dry. They can now be added to the lames to produce bright colors.

Green flame: Borax or Boric acid, copper nitrates or barium nitrates, alum (thallium)

Orange flame: calcium chloride

Red flame: stronium nitrate, some sources site Boric acid as well

Reddish/Orange-calcium choloride

Yellow flame: Table salt, Sodium Chlorate or Potassium Nitrate

Yellow/Green-borax (sodium tetraborate)

Purple flame: Lithium Chlorate, (potassium nitrate)

White: psom Salts (magnesium sulfate)

Another  special effect can be achieved by sprinkling powdered iron into a flame. If this is done slowly enough, a number of yellow, sparkling "stars' can be seen clearly.