Creating your own magic spells and practices should reflect individuality. There are many lovely rituals and magic spells available but a Witch should be able to write his or her own. I read somewhere that using another's magic spell/ritual was like wearing someone else's underwear. Your own magic spells and rituals are tailored to your own needs and use of energy. Although a pre-made magic spell will work, magic spells and rituals created by your own hand will have better results.
Writing your own rituals and magic spells can be very fulfilling. It allows you total freedom to worship the God and Goddess the way you want. You can be assured that you can create a ritual or magic spell for all needs and times. Along with this freedom there does come responsibility!
If you create a magic spell or ritual, eventually you'll want to cast it. Well, have you thought about it? There are plenty of people who cast magic spells everyday. Some are Pagan and others are from a variety of different religions. Wicca believes that everything you do will return three times stronger. If you send out positive energy with your magic spells, eventually you will receive positive energy in response. This is true for negative energy too. So, before you cast that magic spell to give your enemy a boil in an uncomfortable place, think! Is it really worth it? Usually it isn't.
Ethics in magic spell creation are important considerations. Before any magic spell is created, you must think of the spell's implications. There really are just two rules for spellcrafting and they are to do no harm and to not remove someone's free will. Why should we magically remove another's free will or harm someone when mundanely those actions are considered a terrible crimes? It never ceases to amaze me how many people think it's okay to do a negative act magically that they'd consider wrong if committed mundanely. So, think before you put pen to paper!
Another thing to keep in mind is whether you really need to use magic. It's easy to start casting magic spells and conducting rituals for every little thing. Magic is powerful but it's not always necessary or the best alternative. Often magic spells work in unexpected ways. They can also work less promptly than we'd like or have interesting side affects. Magic can also make a situation more complicated. First brainstorm and work out mundane solutions to your problem. Generally it takes less time and less energy to follow through with the mundane solutions. Magic isn't a cure all. The caster has to take an active role.
For example, if you do a magic spell for prosperity, then don't expect money to appear in your wallet or purse. You shouldn't keep spending your money and doing the things you know are not conductive to prosperity. That just defeats the purpose of the magic spell. Instead create a situation that can take advantage of your magic spell. Nor should you think that because you did a magic spell that it will automatically work. There are many reasons why magic spells don't work. Even the most experienced of Wiccans cast magic spells that don't work. I believe that most of the time when a magic spell doesn't work that it is because we have to learn a lesson or that the magic spell wasn't needed. If you are ready to take on magic's responsibilities and accept its disadvantages, begin creating. It is a joyous experience to work with magic and to create the means to work with it. Just remember that it's also a force to be respected.

You need a job, so you say that you will do a job magic spell. Before you even think about casting try all mundane aspects to find that job. Look in the classifieds, ask around etc. If this doesn't work, after a reasonable period of time, then, and only then consider casting a magic spell.
If you do a job magic spell, think that someone else might need it more. A man with a wife and three children who is struggling to make ends meet is competing with you for a job. You cast a job magic spell, and you get the job. He is evicted from his home, his family starve and his children can't go to school. Think of the consequences before you cast.
When you actually decide to cast, make sure you harm none, don't change freewill and don't do a lot of personal gain. When you have almost finished the magic spell, add a couple of lines that make sure its for the good of all, harms none, won't have any bad effects etc, after all, it's your karma. Magic spells and rituals is an important step. Paganism embraces individuality and personal exploration.
For example you want to d a love magic spell, but you *KNOW* that that is a no no, but there are ways around that, not in that you will end up casting it onto someone else, but the fact that it might work. But before you do that, you'd have to try and talk to the person, remember the first question, you have to try the mundane way. If that doesn't work, you decide to do a magic spell, but don't try and bind them into loving you, instead, do a magic spell onyourself so you can accept love more freely.

Ask yourself these three questions before you decide to cast a magic spell:
1) Have I done everything I can to resolve the situation without magic?
Try all the mundane methods of attaining your goals before resorting to spellcraft. If you want a job, send out your resume before you break out the green candles and patchouly. If you want to meet someone special, try reading the personals or signing up for an adult ed class before you reach for the aphrodisiacs. If you're having conflict with someone at work, try talking to them about the problem before you go looking up binding magic spells. As one experienced witch put it to me, "this way, you can be sure that your intentions are pure."
2) Will this magic spell harm another, or bend someone's will to mine?
Please refer to the Wiccan Rede. Witches do not cast magic spells meant to harm someone else. Nor do they cast magic spells on other people without their permission, no matter how honorable their intentions. There's a good reason for this: harmful and meddlesome magic spells have a nasty tendency to backfire on the people who cast them.
When you're watching someone close to you suffering, it can be hard to consider the situation objectively. One reader asked me about magic spells to help alleviate anger. When I dug deeper, it turned out that spellcraft was entirely inappropriate. If possible, discuss the matter with another trusted pagan friend. If there's no one around to consult with, try asking someone in the chat room or the Forum.
3) Am I prepared to accept the consequences of this magic spell, whatever they might be?
Think long and hard about this one. As I've said before, you may cast a magic spell with the best of intentions, but end up with unexpected consequences. Meditate a bit on it before you decide to cast the magic spell. Talk to other witches and see if there isn't a better solution.
Either way, your magic spell has a better chance of success if you fully "own" it, and anything that results from it. The best way to avoid unforseen consequences is to follow the guidelines set out above -- and, most importantly, to cast the magic spell with love in your heart. Making magic is a powerful and transformative experience. In the midst of the magic spell, you become the subject, and you become the result. Make sure that what you're asking for is something you'd like to become.