They paint it as if it's not like Harry Potter or the movies, and that's pretty obvious. Thing is, how does it work? What's it for? What are the limits? If magick is similiar to prayer, isn't it basically meaningless?
When you cast a spell, it sends your intentions out into the universe. You can protect, heal, bring love, bind people, and much more (I can't think of most things), just keep expectations realistic. Adding onto that, magick cannot change DNA (a common expectation of new members), drastically change your appearance or anything physical like that.
Magical practice is real, the effectiveness of it, however, would be subjective. It's up to you to decide. How it works will also vary from person to person and also isn't concrete.
For me personally, magic and witchcraft are practices which help me go about my daily life, whether real or placebo. It keeps things going. It's also a devotional activity.
The function of magical practice can vary from culture to culture to person to person (and practice to practice). For instance, folk magic was usually used by people who were/are oppressed to give them some measure of control, real or imagined, in their lives. It also functioned as a sort of medical role for poor communities with no doctor. The local witch or worker, or even just a traveling one, was important for these and other reasons. Of course, you did have some charlatans, but it'd be unfair to call them all charlatans. It'd be like calling every doctor a quack. Nowadays, this role is diminished because of modern medical science (in some places).
For some, it's a spiritual practice, something moving them closer to their spiritual self. And some people use it in conjunction with their religion to feel closer to the deities or spirits they love, or to again, have a more rounded spiritual life. None of these reasons mentioned are exclusive to one another.
A good little mantra to remember comes from my favorite Aesop fable, Hercules and the Wagoner. The Gods help those who help themselves. Essentially, no matter the practice or the situation, if you work it with magic, you have to work for it with magic not by magic. Don't rely solely on a spiritual practice to get your work done. You have to put your nose to the grind stone too, your back to the wheel.
Limits are usually set by the practicer. A general rule of thumb is to spiritually work for possible things, a good Delphic Maxim to keep. Some people, such as myself, do divination before a spiritual working to see if this is the best course or if it would produce any fruit.
There are many reasons to practice magic. Saying prayer is meaningless is a little derogatory to religious practices. It's an unneeded statement. Prayer and spell work can be compared, but the methods of magic are different as they do not need to call upon an outside source to do the work. Prayers are petitions to spirits or deities. They can be similar; both are an attempt to change something within the world, self, or your life through indirect means, an intermediary, that isn't provable by scientific thought.
Eh, to add, the local witch or worker could do other things for the community than just perform as a spiritual healer. They could have a speciality, like love work, or be a well rounded individual. It varies.
Magick in real life really has nothing to do with the movie series Harry Potter. It is very useful for so many things as in healing, talking to spirits, good luck, stuff like that! For me spells work better if it is a good spell. If you do a bad spell (revenge, death, hurt, etc) there would be a high chance of it backfiring or it not working. But no it is not meaningless magick means a lot to many people who don't believe in God or that actually do believe in him. The reason of that is there is a good way of doing it on your own and God does not answer all prayers he listens but not all of them he fixes for the person for any will. These are good questions but easy to answer.
I would add my say in this, because it is quite clear that there is some anti-Christian bias in here, and would like to clear this up.
The Divine; whether that be Allah, Buddha, Shiva, the Kami, the Christian God, sometimes referred as Tetragrammaton, or even Satan himself, are beyond complete comprehension.
Their goals are shrouded from us, but their existence is at balance and is mostly because of us. Our needs and our energies give them a reason and need to exist, but they have their own ends. They are not our servants, nor are they completely our masters. There is different lengths of devotion and acts of ascendence, but as a general rule, all of them live in harmony with us.
Harmony however, is not what many believe it to be. For each positive, their must be a negative. For each act of aggression, there is an act of compassion. For love, there is hate. For life, there is death. We live in a universe of scales and our wishes and whims are interpreted differently on the cosmic scale than we may like to believe.
The firm, but harsh truth, is that the Divine will often act for us when our need is great for them, but they say a picture we cannot completely fathom. They have given us tools to work this picture to our intent, aka Magic, but it is ultimately they, the collective whole of the universe, that interprets what our desires and true needs are.
Many whom claim that they don't answer prayers, have not realized that often they have been answered. Asked to find true love, but find a swindler and a cheat? Would you say it was an answer? To the common man, no. But to the divine, it was, because your heart now knows what true love "is" and will help you find and act on it in others.
It is not a cut and dry service and it is a path that make take the rest of your days to understand that the path you walk was given with the best intentions and every stone was laid before you with purpose. People vex the gods for every small problem that arises or when tragedy strikes, and it is a time for mourning and grief, but these moments are meant to build us and make us stronger. Not to lose hope or faith.
Magic hardly exists in the idea of what the common people think. Magic is life and will given shape, in a world where our will harmonizes with the will of the divine, on a path some may only call as Fate.