Mirror mirror on the wall...
If you've managed to successfully learn the techniques to skry then using a black mirror shouldn't give you any problems. I place the mirror at such a distance so that it's at a 45° angle whether it's standing or laying flat. Why? Because 45 corresponds to Saturn's square. Saturn's energy relates to the higher self. This should be done at night or in a dark room. Place two candles at a far enough distance so that no light refracts on the mirror's surface. You must not be able to see a reflection of any kind in the mirror. No major rituals need to be performed if your just beginning. Ritual work should only be done if you're working with evocation of any kind. Do this if you need to feel safe. Skrying can get pretty intense.
Begin by meditation to clear your mind. Once you're in a relaxed state open your eyes and gaze at the mirror. Don't look directly at it but let your eyes go out of focus. Imagine that the mirror is like a deep pool. Over time images will begin to surface. These images may not have any structure to begin with. They may just be flickering lights. This is from your third eye beginning it's development. Be patient. If you don't achieve results right away keep practicing. Over time these flickering lights (or even mist) will start taking shape. You may see people or places new and familiar to you. Don't try to communicate with the images. If you communicate with them then you'll create a link to the spirit world. Remember the old adage "Never talk to strangers." Become familiar with the images you see before communication takes place but not before you're ready.
As a word of warning. Don't expect the images to remain in the mirror. Often they will come forward through the glass and into your temple. on't be quick to think that these images you see are here to benefit you. These images are visual manifestations of the Astral world which you are connected to. They are aspects of your own thoughts and emotions. Be aware that at some point you may encounter aspects of yourself which you are not ready to face. That aspect of yourself which is denied by the ego is what people have termed "demons" which are nothing more than the self's dark reflection of a primal human nature.
Banish the energies when you're done with your experiments. Always ground yourself after using your mirror. When you become more adept at skrying I recommend that you try working with spirits written in grimoires.