It is said that spells made by you are more powerful because they are entwined with your energy and are custom made for your situation. You will also feel a stronger connection with a spell you make yourself then one you use, because it is your own work. Below are the parts for a spell; when writing a spell these parts should be noted and included. (Ingredients & description part is optional)
Name: The name usually states the purpose or outcome of a spell such as Rain Spell. The title should be short and do a good job at summing up the purpose.
Description: The description is where you can more in depth about what the purpose and outcome will be of the spell. This clears up any confusion that the reader may have had from the title.
Ingredients: The ingredients for a spell are merely suggestions and are not required. If you have them, fantastic. However you dont need to use anything unless you desire to. Even if a spell revolves around a specific ingredient, you can visualize the ingredient in your mind and pretend that you have it. Note that some spells dont require ingredients.
The Spell: The actual words or actions to be preformed for the spell. This is usually presented in steps to tell you how & when to use the ingredients, what to say, and anything else you will be doing for the spell.
If you would like to get more into depth when writing you spell, you could also use the correspondances listed below. For example, if you were creating a love spell, then you might want to put down that the spell should be done on Friday, as Friday is the day of love. The color correspondances can be used in any way you please. Using the Love spell as an example again, you could write the spell on red paper to correspond to love.
Correspondences 103 - Colors
Correspondences 104 - Days
I would also suggest taking a look at this post:
I hope you spell works out well, blessed be.