it's morally wrong, but it is possible to do. spells cast over another interferes with their will in some way. love spells being the most common, but even casting a healing spell without the persons permission is going against their will so many people see casting over others as morally wrong.
manipulating another through a spell can be done, but what are you wanting to do? it could fall into a category [luck, love, wealth, protection] if you want someone to go away, a banishing spell will make them feel uncomfortable when they get too close, keeping them away. [love spells, the opposite effect, they're drawn to you] a spell to, say, control them whenever to do whatever you say, this can be a lot harder, and i don't think it would work 100% of the time.
i am reminded of the 'Witches Handshake' you're suppose to shake the persons hand with your power hand, touching their pulse [or close enough to it] with your middle finger and think something really strongly like 'hire me', 'love me', 'agree with me' short and to the point. i have used it once after a long job search and it worked [since i did get the job] but with just that one time 'success' i can't say it works or it was just my imagination. try it out for yourself, it couldn't hurt any... unless you tell the person to hurt them self...