patience is one thing
also if you doubt it
it won't work maybe you think one thing but your subcouncious mind is working on something else
our feelings have a lot to do with it (and our ego)
practice, learn about your self maybe you think i know my self but you can be wrong about that!
meditate this helps a lot before doing a spell
btw i would firstly learn more about what i am working with before casting any spell
btw this is all my thinking and personal opinion(also about personal experience)
maybe other's can tell you more about it! and help you out!