Depending on cultural tradition, the distinction between Black, White, and Grey magick may fall under either of two sets of definitions. I'll separate them not by colour, but by the orientation:

Version A:

White Magick consists of spells which are directed solely on goals for self improvement of body, mind, and spirit. Forces of energy are not used on others or directed in such a way that they may affect others. Example: calming one's own nerves, improving one's health and happiness in general.

Grey Magick consists of spells cast to aid others who have either requested help, or who have granted your permission to do practise on their behalf. Example: to help an ill friend suffer less discomfort, or hasten an end to their financial woes.

Black Magick means casting spells to influence people or things without their knowledge or permission. Under extreme circumstances, in which one's own life or health is at stake if defensive action is not taken, this would be considered the course of action. As you might expect, this is far less applied than white and grey types of magick, and even then the Rede is taken into consideration and respected. Example: A person who continues to cause you or your family hardship despite conventional efforts (Still, rather than having something conducted to outright chase the person away, an effort would usually be made first to focus on eliminating the negative energy and hardship being caused). Usually, if the subject is meant to be eliminated from another's life path, then they will move on to other exploits. Directing on a specific person or thing must only be applied as a last resort when all else fails.

Version B:

White Magick is productive: Attracting and receiving by nature. Examples: Improved health, more money, better weather, etc.

Black Magick is destructive: Removal or deterrant. Examples: Elimination of a tumour, removal of bad vibes in a troubled household, etc.

Note that Black Magick is not used for greedy, malicious, or manipulative intent under either interpretation. It still involves responsible and cautious directing of energy.

And of course, common sense would suggest that magick not be used in place of conventional resolutions (like looking for a job or seeing a doctor). At best, magick may be used to enhance your prospects.

If praying is what you'd have done for many of these examples, then BINGO! You've made the universal connection bridging the faiths, for what else would magick be?

Naturally, adverse consequences of aggressive magick may not return to you exactly threefold as poetically decreed near the end of the Rede ("Mind the Three-fold Laws you should; three times bad and three times good"), but expect fallout. It may not hit your person directly to impact your life, but someone close to you.