Try with something easy, you've never cast a spell, and spells use energy!
Do you know the basic's? If so, ask yourself these three questions.
1) Do I know what I'm doing?
2) Am I experienced enough? Do I need help? Do I have supplies?
3) Do I have enough energy, and belief?
These can prevent some things, as well as help. If you really want to do a spell, please don't do a dragon one. It can be dangerous, and I suggest learning basic's and first starting a spell is say luck?