For my story I'm using a pretty "soft" magic system. Basically I'm taking the old school notion that magic is the manipulation of spiritual entities. I believe Harry Dresden would call it something like, "two-bit sorcery." But, in my world, that is how practically all magic works. (Still toying with the idea of alchemy, but need to look into it more)
So...basically you can't "point and click" to do something magical. For example, let's say you wanted to burn down a warehouse full of your enemies. There is no whispering of an archaic phrase to spew a fireball. What you'd need to do is summon an entity of some sort that's capable of manipulating fire (it could breathe fire, or maybe it's a living construct of flame, the possibilities are limitless) and coerce into starting the conflagration. One can compel a spirit or demon to do something through intimidation, cajoling, flattery, or spinning a deal. (I'll scratch your back, you scratch mine.) It all depends on who's involved and what's at stake.
Spiritual entities run pretty much the whole gamut of the imagination. Some entities are very human, some show intelligence more like insects or animals, and others are more like forces of nature with no real desires or feelings.
To do magic, you reach between the veil of the real world and the nether world, contact and summon one or more such entities then compel them to follow your orders. How does one accomplish this? Every human being has the basic equipment needed for magic: the soul.
For an analogy, imagine your soul as a blazing firebrand that you can use to lure and hypnotize a beast from the woods. Said beast is drawn towards the fire, but also afraid of it, thus you can keep the creature at bay, command it by prodding it with the fire, and (hopefully) keep it from trying to defy you and destroy you. If properly directed, a human being can use their soul to "burn" a supernatural entity and cause it pain, in the same way they could use a firebrand to burn a flesh and blood wild animal. (Think Belowulf vs Grendel)
In the early days, human beings learned to do magic as part our natural development, just as we learned to use fire or make arrow points. Any archeologist can tell you that most ancient cultures harbored a widespread believe in the spirit world, and many had go-betweens, usually in the form of shamans. They were the first sorcerers. Every culture in the world has their own way of doing magic, with their own trappings, but in the end it comes down to mastering one's mental focus and controlling otherworld beings.
As a side note ::anybody:: can learn magic. Children sometimes do magic without even knowing about it. Horrific visions of the boogey man or child disappearances can sometimes be chalked up to a kid with a vivid imagination and strong will accidentally contacting something from beyond. Of course this "accidental magic" isn't always bad. Roger Woodward was a 7 year old boy who survived after falling over Niagara Falls with nothing to protect him but a life preserver. (Not making this up
http://www.infoniagara.com/other/history/roger.html) Maybe there was a little bit of magic involved there…However, as we grow and lose that child-like sense of wonder and fear, the likelihood of accomplishing these magical feats diminishes.
My MC is a 17-year old kid, just learning magic. I'll give 2 quick examples of the magic he weaves to show you the feel I'm going for:
With one spell he summons an invisible demon spirit that makes him invisible as well, to hide from some bullies. The experience is terrifying, and while invisible he's aware of winter-cold claws gripping him, and feels like a dove caught in a predator's jaws. He doesn’t quite know what he's getting into, and once the spell is over, the demon claims its payment for services rendered. It stalks down one of the bullies and attacks him by wracking him with seizures that put him in the hospital for 3 days and leave the young man with a permanent facial twitch. Consequently everybody thinks it was a natural sickness. (Trying to embrace the old school notion that sickness could be brought on by demonic influence.)
For another spell, the MC tries to construct an oracle to keep tabs on some baddies. He sharpens a stick at both ends (ala Lord of the Flies) and mounts a pig head upon it that he bought from the market in the Little Mexico suburb. After many hours of trying to contact the spirit world, it finally comes to life when some entities speak through it. The decapitated head whispers strange things to him then lets out a horrific shriek and bursts into flame.
The MC is terrified and has no idea what this means. He considers the spell a failure until much later when he sees that the oracle was giving him clues, just not the ones he'd been looking for at the time.
Anyway…sorry for the longwinded explanation. I'm trying to present magic as something mysterious and dangerous. I just wanted to see what people had any opinions or suggestions they'd like to share. Thanks in advance!