Please, future spell-practitioner, read this carefully if you want to cast a spell with bad thoughts on your mind and in your heart (e. g. if you want to harm someone, control someone, control the weather…).
Spells don’t work like that. Moreover, when it comes to e.g. Wicca, this religion isn’t centered around spells because the spells are nothing less than a manipulation of energies around and within us.
It is way better (and ethical) to cast spells with good intentions. I strongly recommend you to write them by yourself, because you know your intentions better than anyone else. Secondly, the key is in visualization, and not in the words. You need to focus your energy and direct it to something good.
Of course, spellwork needs a lot of practice and knowledge. It can’t be achieved in a day or week because you have to learn it thoroughly!
But first and foremost, you should learn to control your mind and direct your thoughts and energy to something that won’t harm anyone.
Needless to say, don’t forget to always respect the Mother Nature and her power(s).
~ Blessed be ~