A new candle must be used for each new spell.  The candle must not be cracked, broken or damaged in any way.  Make sure you have time when you plan to do your candle magic, because the candle must be allowed to burn out on it's own and you should never leave a candle burning unattended!

Using herbs or herbal oils with your candles can increase your candle's power.  For increasing magic, before the candle is lit, rub candle with appropriate herb(s) or herbal oil(s) from the bottom to the top of the candle. 

Before you light your candle, clear your mind of all thoughts except for the intended need.  Let the match burn out in a fire proof container such as an ashtray, don't blow it out.  Once the candle is lit, imagine your need manifesting as the flame burns.  Pour your energy into the flame and concentrate on the task at hand.  A single pinch of herbs (any more than that is a waste and a fire hazard) can be sprinkled into and around the flame in addition to or instead of any herbal rubbings.  Be sure the herbs you use have the correct properties for the needed spell.  Do the research if you want to use herbs.  Don't use an herb if you don't know what it does, you'll only defeat the purpose of your intentions.

Yellow:  Activity, creativity, unity; brings the power of concentration and imagination to the success of a ritual; use in rituals where you wish to gain another's confidence or persuade someone or in rituals that require solar energy.

Gold:  Fosters understanding and attracts the power of cosmic influences; beneficial in rituals intended to bring about fast luck or money, or in rituals needing solar energy.

Pink: Promotes romance, friendship; standard color for rituals to draw affections; a color of femininity, honor, service; brings friendly, lively conversation to the dinner table.

Orange: Charges and recharges the intellect; combine with any other candles to stimulate their action; for rituals stipulating Mercury energy, and sometimes solar energy.

Red:  Health, passion, love, fertility, strength, courage, will power; increases magnetism in rituals; draws Aries and Scorpio energy.

Silver:  Removes negativity and encourages stability; helps develop psychic abilities; attracts the influence of the Earth.

Purple:  Power, success, idealism, psychic manifestations; ideal for rituals to secure ambitions, independence, financial rewards, or to make contact with the spiritual other world; increases Neptune energy.

Magenta: Combination of red and violet with a high frequency; energizes rituals where immediate action and high levels of power or spiritual healing are required.

Brown:  Earthly, balanced color; for rituals of material increase; eliminates indecisiveness; improves powers of concentration, study, telepathy; increases financial success; locates objects that have been lost.

Indigo: Color of inertia; stops situations or people; use in rituals that require deep meditation; or in rituals that demand Saturn energy.

Royal Blue: Promotes laughter and joviality; color of loyalty; use to attract Jupiter energy, or whatever an influence needs to be increased.

Light Blue: Spiritual color; helpful in devotional or inspirational meditations; brings peace and tranquility to the home; radiates Aquarius energy; employ where a situation must be synthesized.

Blue: Primary spiritual color; for rituals to obtain wisdom, harmony, inner light, or peace; confers truth and guidance.

Emerald Green: Important component in Venusian rituals; attracts love, social delights and fertility.

Dark Green: Color of ambition, greed and jealousy; counteracts these influences in a ritual.

Green: Promotes prosperity, fertility, success; stimulates rituals for good luck, money, harmony, and rejuvenation.

Grey: Neutral color useful when pondering complex issues during meditation; in magic, this color often sparks confusion; it also negates or neutralizes a negative influence.

Black: Opens up the deeper levels of the unconscious; use in rituals to induce deep meditation, or to banish evil or negativity as in uncrossing rituals; attracts Saturn energy.