The only thing necessary in casting any magick is you.
Will, focus, belief and knowledge. If you're not naturally adept in throwing magick, you will need to practice the basics of energy manipulation--charging, shaping and sending--as well as the basics of your own spiritual wellbeing--grounding, centering and meditation.
Ingredients, correspondences, and ritual are all just tools--a way to mentally accept the change/goal we wish to make. Magick is mind over matter in essence, but some people need to see something in order to believe it, which is why we use spellwork/rituals.
Words, sounds and music meet our auditory needs.
Colors and tools, clothes, jewelry meet our visual needs.
Actions make us feel as though we are physically productive/making a change.
Specific times, herbs, etc are a way to rationalize that these objects will help us (giving us more confidance and boosting belief)
These are all ways to help our mind and emotions.
I'm not without that need for ritual at times, but they are very simple and I rarely write them anymore. I perform rituals intuitively (unplanned). However, when my emotions are strong about a subject, I don't need anything other than the key ingredient (myself).
So writing spells successfully is about knowing yourself and stimulating the mood and focus you need based off of the way your mind works. Do what feels right and what makes sense.