Magic is never guaranteed. You can have a strong desire and all of the right supplies, and it still might fizzle out on you. There are many reasons why this can happen -- some that are within your control, and some that are not. Here are some of the most common reasons why a spell or ritual might not work, and how to prevent them:
1. The timing was off.
It is always better to try to align your spell or ritual with the right timing. This can be complicated, and often means that there might only be a narrow window once a year when your spell has the best chance of succeeding. Obviously, you might not be able to work within this tiny window of time, and that is okay. You should still try to have things line up as much as possible.
For example, working during a waxing moon is best for increasing things. A waning moon is best for decreasing them. The full moon is when the moon is at the height of its power. The day of the week can be significant, as can the hour. During the day, the hours between midnight and noon are best for increasing. The hours between noon and midnight are best for decreasing. Each hour is also ruled by a planet, so choose the hour that corresponds to what you want to achieve. Lastly, the sun and moon also move through the zodiac. Each sign has its own magical associations, so you may wish to choose a day that is in the correct sign for your spell.
If you need to cast an emergency spell, you may not be able to make the moon phase, time, day, and zodiac align. That is okay. Mistimed magic can still work, it just has to work a little harder.
2. The colors were off.
Colors carry strong magical associations. When you see pink, for example, it conjures up images of love, romance, and softness. You would not want to use pink if you were trying to banish an enemy from your life! Every color has its own properties that make it better for some spells, and worse for others. With the exception of white, you cannot substitute one color for another and expect the same result. Know your colors, and choose the correct candles for your intent.
3. The statement of intent was not focused.
Magic is intended to bring your desires to you, so it is incredibly important that you know what your desires really are. You may do a spell to get money, when what you really need is a new car. Focusing on your true desire gives your spells more room to work -- there may only be a few ways for you to get money, but there are many ways a car can come into your life.
When you are thinking of what you want, always ask yourself, "Why?" When you can reduce your desires down to their most basic form, you can focus your spell more effectively and increase your chance of success.
4. The herbs were off.
There are a lot of lists and charts of herbs and their magical properties, and they can be misleading. Roses are used for love magic, yes, but their color dictates what kind of love they attract. Not every herb that falls under a certain magical category can be swapped out. It is always a good idea to properly research the traditional use of your ingredients before you decide which ones to include. You may find, for example, that the money spell you have worked to attract a new job actually used herbs for luck in gambling. You do not have to follow traditional herbal grimoires to the letter, but choosing the correct herbs helps.
5. The method was incorrect.
When it comes to magic, the way you do things is just as important as what ingredients you use. This is even true for the way you dispose of your spell remnants. If you want to banish someone from your life, you do not want to bury a spell jar in your back yard. If you want to attract a lover, you do not want to toss your candle stubs in a dumpster across town. Disposing of your spell remains is part of the ritual -- make sure you choose the right method.
Spells fail for a lot of reasons. If you want your spell to work, it behooves you to do as much research as you can, time it properly, choose the right ingredients, and make sure the remnants are properly disposed of. All of these things will give your magic the best possible chance of success.