With the "Nature of Magick" in mind (if you haven't read it, make sure you do; it will help you understand how this works), the first thing involved in casting a spell is to figure out EXACTLY what you want to accomplish. This isn't as easy as it sounds. You really need to be very specific in what you want. Do some real soul-searching about it; write everything down as you go along.

Take your desire/goal and tear it down into tiny pieces, ask yourself if this tiny piece is part of what you really want. Do this for every aspect of your desire. When you're done, you may find out that your goal is a little bit different than you first imagined.

If you don't know what your true desire is, you may accomplish the spell you set out to do, but still not be happy. For example: you may cast for fame and fortune and people fawning all over you in a chosen area; you accomplish this but are still unhappy. Why? Because the self-love and/or loving relationship (which is what you wanted to begin with if you would have looked deep enough) needed to enjoy your life isn't there. Do you see what I mean?

When you're done with this, think of every single person that will be/is involved in the results of this spell. How will it affect them and their lives? Will it be the cause of any possible kind of harm to them? This includes yourself.

As far as how your goal will be delivered -- don't plan that part; Don't tell the "powers that be" how you want it done, just that you want it done. As long as you have determined that no one will be harmed by the results of this spell (that your benefit won't come from the misfortune of another, for example), the Universe, or your preferred deities, will decide the best way to achieve the goal. Don't get me wrong, you can't just sit back and wait around for the results of the spell to dropped in your lap, you have to put some mundane, everyday effort into it as well. Say your spell was for the perfect job for you. You can't sit at home and expect someone to come to the door and say "Hey, have I got the job for you!". You have to get out and let them know you're looking, set up interviews, etc. You can't expect to find a job, or a relationship, or whatever it is you want, no matter how many spells you cast, if no one knows you're looking!

If you're satisfied with the goal you've decided upon, and the answers you've come up with, then go ahead and write out/plan the rest of your spell.