Magic, or "mage" as it is commonly called, can be a very long, hard skill or a very quick, rather easy skill. It all depends on the methods you use or the amount of money you want to spend. Below are various ways on how to train the skill, with brief ideas of how long they will take and how much money they will cost you.
Alchemy, or "alching", is a common way that people train Magic. The idea is that when casting alchemy on an item, it then turns the item into a set amount of gold pieces. This spell gives 65 experience per cast and can also be used with noted items so you will not have to go back and forth into the bank. It is designed so that you can easily repeat the spell efficiently. This method, if done with the right item, can make little money, although most people find this very boring and thus get distracted and do other things. This causes this method to generally take a while. If you stay concentrated the whole time you are logged in, with no distractions, this method can usually be decent experience. This method of training requires little to no attention as you are simply clicking in one spot, as such it is recommended to watch a movie or something of the sort in order to alleviate boredom and maintain high xp rates. Casting the high alchemy spell requires Level 55 Magic, and takes 5 game ticks (3 Seconds), meaning that it can be cast 1200 times each hour, for 78, 000 Xp every hour, at maximum efficiency. The spell uses 1 Nature rune and 5 Fire runes, so it is recommended to use a Fire or Lava battlestaff, or a Fire staff when casting. As the price of Nature runes if usually between 50 and 300gp, the trick to gaining profit while 'alching' lies in finding items that alchemise for more than their price, common examples are metal armours, bows, and battlestaffs. Note that there are two types of Alchemy: High-Level Alchemy and Low Level Alchemy. The term "alch" usually refers to the higher level equivalent.
Fist Of Guthix Minigame
The Fist of Guthix Minigame can be an effective and cheap way to train magic. This SAFE Minigame consists of two parts. In the first part you must equip a stone of power, survive as long as possible while being hunted by another player, and collect as many charges as possible. In the second part, you take the hunter role to kill your opponent as soon as possible. You are given free runes to cast spells within the arena, so there is no cost for the experience. During play, the hunter's stats are boosted, and the hunted's are weakened, meaning it is possible to defeat players with higher levels than yours. The rewards, Fist Of Guthix tokens, can be used to purchase and recharge rewards. Rewards include combat gauntlets, medium level mage and prayer armour, and gloves that give extra XP in Slayer, Fishing, and Runecrafting. The degraded armour and gauntlets are trade-able, and the high level gauntlets sell for a high price, making it possible to convert your tokens into money if desired,
Teleport Tablets (Members)
Another way, which is slow experience, yet fairly profitable, is to make teleport tablets or commonly known as "teletabs". These are made in a Player-Owned House on a Lectern. These tablets can be made to teleport the player on breaking to the defined destination. Doing so will give the same XP as what the spell itself would give you. The player will combine the runes into a Soft Clay, making the tablet. This can give the player a fairly large amount profit if you have your own, as you can use the butler to fetch soft clay for you.
Charging Orbs (Members)
Yet another slow, but profitable method to train Magic is to bring an inventory of unpowered glass orbs to an (Air, Fire, Water or Earth) along with 30 elemental runes that corresponds to that Obelisk (or a staff), and 3 Cosmic runes per orb. There are four Obelisks, one for each element (Air, Fire, Water & Earth) and these all have separate locations; The air obelisk is found in level 7 wilderness (accessible through Edgeville dungeon only), The water obelisk is found just of the shore of Catherby and is reached either via a mithril grapple from the shoreline or by travelling through the entire Taverley dungeon, The earth obelisk is found in Edgeville dungeon, just south of the black demons, this is in the wilderness so don't risk anything you don't want to lose, The fourth and final elemental obelisk is fire and is found in the Taverley dungeon, near the black dragons.
This method of training magic is commonly used by Members and Non-Members alike. This method uses the spells Curse, Weaken and Confuse in Non-Member worlds, or the spells Vulnerability, Enfeeble and Stun for higher levels on Members worlds, with Stun providing the best experience to coin ratio. This method is employed mostly with the use of metallic armour (or sometimes Sacred Clay melee armour on Members worlds), which reduces the players magical accuracy, allowing them to "splash" with the spell. If these spells hit, they cannot be cast against the same target again for a period of time, so for most forms of this training, having such a low magical accuracy would be highly beneficial.