Writing your own spells is what every practicing Witch aspires to. The ability to craft your own spells gives you an advantage over “ready made” spells you can find in other places. This is because you will be putting your own emotion and energy into the spell. Through the process of its unique creation it will be special and meaningful to you, and that is the secret of casting successful spells.
If you want to learn black magic, all of the following holds true. The ingredients and tools that you use are purely dependent upon not only what traditional magickal properties they might possess, but also what they mean to you as far as symbology goes.
There are different ways to set up the wording of your spells. They can be as simple as a two line charge to enforce your will, rhyming couplets (my personal favorite, since it helps me to better remember the words without referring back to written instructions), eloquent and lengthy prose to charge the spell to the energy of your will, or simply the use of repeating or chanting a single word over and over again.
Everything that you put into the spell, the ingredients, the words, the time of day, etc come together with your desire, emotion, and belief to bring about your desired outcome (sometimes within a day).
A quick word of warning: you should steer clear of casting spells to harm or control other people in any way. Not only does this go against the Witchcraft Ethics and Responsibilities, but trying to control someone else (or cause harm to them), opens doors in the future that you may not want opened. I have seen people lose everything because they practiced Magick in ways that go against common morality. Always make sure your heart is in the right place, and that you feel good about casting a spell.
Now, here are the things you will want to do while creating your spell. Make sure to write down an outline for the spell on paper so you won't forget anything. Even if your spell sounds silly as you write it, keep writing, as long as it is coming from your heart, and is for an intense desire that you have. Unless it is an emergency situation, plan out the best timing for when to cast the spell. You will need to take into consideration planetary influences, moon phases, etc. When you have finished your spell, write it down in your Book of Shadows. Record the results of your spell, and any feelings you had while casting it in your Book of Shadows Revise the spell as necessary, as you figure out what went right and what went wrong.
I hope you found this quick guide helpful! It really is not that complicated. The most important part is that you create something that is authentic to you.