This is one of my favorite areas of magick, so I want to know why you went ahead and created one without knowing much on the subject? o_O If you had specific questions, that might help us.
Servitors can grow very strong with time; the more thought you give them the more they Are. I think there is some shady misconception that servitors are dark and whatnot, but I have one who is perfectly 'nice'. It depends on their purpose; they don't have to be these big boogiemen type creatures. They're effected by their creator's energy. If you're a volatile or unstable person, emotionally and/or energetically, expect your servitor to be so. They need regular energy to 'live', but you can also give them a designated energy source (like fire, cat hair in the carpet, whatever), so have fun with it.
Respect them as you would anything else that you made, and when you are 'done' with it send the energy into something positive.