Everybody has ethics of some kind or another, and it is important to identify these ethics and consciously apply them. 

The first I want to mention is the confusion on White vs. Black magic. 

White Magic, Grey Magic, and Black Magic all have varying meanings to many different people. How I have always seen it is rather simple...

White Magic: Is magic that is used for the benefit of you or others such as blessings, healings, readings, assistance, etc.

Grey Magic: Is magic that is used that is fairly neutral in nature, could be either good or bad depending on situation and perspective, but ultimately is just neutral such as enchantments, readings, altering the weather or situations etc.

Black Magic: Is magic that is used to cause harm, misfortune, pain, loss, or anything negative directly upon someone else either out of anger, revenge, or to steal something from them for your own personal gain.  Using magic to justify in an act of avenging yourself or another is still catagorized as Black Magic. 

Now that we have covered White-Black magic, Lets talk about the rebound rules.

This has multiple different names but ultimately it is all the same. 

"The Golden Rule", "The Rule of Three", "The Rebound Law", "Karma", "Wiccan Creed", "Ten Fold Rule", etc.

Ultimately whichever one(s) you choose to follow represent the concept that anything you put out into the world you will get back onto yourself. If you are kind to others, others will be kinder to you, if you seek to curse or ruin others, others will seek to ruin and curse you, If you bless others, you will be blessed, if you lie, you will be lied to, if you be a friend, others will return the favor. etc.  So with that in mind now, keep it in mind also when performing magic. If you cast a curse that someone will have an accident, be prepared because when you least expect it the chances of you having an accident are increased that much more by the amount of energy and power put into that curse.  If you cast a blessing upon someone who may be ill or struggling, when you least expect it you, too, will be blessed in what you are struggling with. However if you go around blessing others and casting healing spells just to gain that for yourself at best nothing will happen, but it is likely you will get worse or fall into even more bad luck because you are seeking that personal gain out of magic. Magic used to genuinely help others must be a selfless act. 

It is advised against to practice magic that is not a part of your own faith or path. If you are Christian, Invoke the Holy Trinity, Christ, angels, saints and your guardian spirits when doing any invocation or calling assistance instead of turning to some unfamiliar entity, and if you are Wiccan invoke the tripple goddess, or whichever gods or goddesses you affiliate with. If you are Native American, invoke the Great Spirit or Mother Earth, etc. 

Magic does not belong to any one religion, faith, or sect. it is a part of life and if you were truly born a witch or wizard you will have already known this. Now also keep in mind the code of ethics or creed, guidelines on which you live your life with your faith and apply that to your practices.