Mining is the profession of extracting ore from asteroids; these ores can then be refined into minerals which in turn are used in the production of all player created items in EVE, such as ships and modules. It is one of the few professions that is immediately available to beginning players and most EVE industrialists started their careers by mining. Mining is perhaps the most economically safe professions in EVE; losing mining ships or being podded is uncommon and minerals are always in demand. In its simplest form, mining can be accomplished by finding an asteroid site in a system and mining its asteroids with mining lasers.
Before mining, it is best advised that players determine what is the most profitable way to mine. This involves determining what asteroids to mine, where to find these asteroids, which ships (and skills) are best suited and optimized to mine and (in most cases) how best to haul the ore to a refining station and then to the market. All miners should attempt to maximize their efficiency (and therefore their profitability) which is typically measured by the amount of m3 mined in a cycle of a mining laser. For example Veldspar is the most common and cheapest ore in EVE and has a volume of .1m3, Scordite is the next most common ore but has a volume of .15m3. Therefore, for every cycle, 3/2 more Veldspar is mined than Scordite. To be more profitable Scordite's market price must be in turn 3/2 greater than Veldspar. Since the market is player driven ore and mineral prices are ever changing, hence miners should always check the market for the most efficient ore/mineral to mine for.
A good site that will help you determine the most profitable ores is Grismar's Ore Chart. Look up the market prices of the minerals from your console, and input them in the top row. Hit Apply, and you'll see which ore will give you the most ISK per m3.
Asteroid belts can be found in most systems either on the overview window or by right clicking and using the Asteroid Belt section(Ombey's 2D Maps contains information on the number of asteroid belts in a system). Each asteroid belt has several properties: what asteroids compose the asteroid belt, what asteroids are present and the overall quantity and quality of the asteroids. In empire space there are six asteroids: Veldspar, Scordite, Pyroxeres, Plagioclase, Omber and Kernite. However only a subset of these six asteroids can be found any system depending on which faction controls the region. Low-sec and 0.0 space each have their own respective set of asteroids (which is compounded, so low-sec space contains all the empire space asteroids and 0.0 space contains both empire and low-sec asteroids). A complete list can be found at ToxicFire's ORE Map. Keep in mind that asteroids only spawn after downtime so there will be belts that are devoid of a certain asteroid (or any asteroid in some cases) because other miners have already mined it out.
Missions also often yield significant asteroid belts. Keep an eye out for those, and you may reap in more ore than a couple of belts combined.
There are three types of ships used in mining: a mining ship, a hauler and a mining support ship. In general any ship that has a turret slot is capable of becoming a mining ship. Caldari ships typically make good mining ships because of their CPU capacities but each race has a frigate with mining bonuses and typically players will receive one upon completion of the tutorial mission. Popular mining cruisers include the Caldari Osprey and the Gallente Vexor. Players will then typically move on to Mining Barges and then to Exhumers. A hauler's purpose is to take the ore that has been mined from a mining ship and transport it back to a refining station or to the market. Usually players will use a industrial ship while mining and a freighter when move large quantities of ore/min from station to station (freighters cost upwards of a billion isk to operate and cannot haul ore from space, so most players will use a industrial ship for both purposes). Finally, a mining support ship can either come in the form of a security detail against rats and players looking to steal ore or as a ship designed to provide mining efficiency bonuses.
There are several methods commonly used in mining, the most basic only requires one account and can be run by very low skill players while the most advanced will require multiple players all performing separate tasks in order to be effective.
The most basic way to mine is to fill the cargohold of a ship full of ore and then return to a station to drop it off. Its advantages are that it requires only one character, is possible for very low skill levels and is completely theft proof. Its disadvantages are that most cargoholds are very small and you are not profitable during the times you are ferrying the ore from the belt to the station. If cargohold mining, try to find a ship with a larger than average cargohold with multiple low slots which then can be fitted with expanded cargohold modules. Cargohold mining is typically not recommended since the amount of travel time (and thus time not spent mining) is so great. A variant of this method is called AFK mining where a industrial ship is equipped with a single mining laser (as all industrial ships only have one turret slot) and then is used to mine a large asteroid while the player is AFK; some corporations have policies against AFK mining and it should only be attempted in low traffic high sec regions.
Jet Can Mining
Players can jettison items within their cargoholds into space, which results in a cargo container (more commonly called a jetcan or just a can) forming within 2,500m3 of the ship. This jetcan holds up to 27,500m3 of space which miners take advantage of by transferring the ore in their cargoholds into the jetcan. Typically a player will fill a jetcan with ore, and then swap to a ship with a larger cargohold (most often a industrial ship). Its advantages are that you decrease your travel time significantly from the cargohold mining method. Its disadvantages are that jetcans only have a life span of about an hour (longer if they are named). Furthermore jetcans are not secure, meaning that anyone can open and move items held within a jetcan. This is a common form of theft and griefing in the game where a player will "flip" a jetcan either to steal the ore or to induce a fight without concord intervention. One possible way to combat this is to use secure containers which can be programmed with a password; unfortunately, the largest, the giant secure container (usually called a GSC) can only hold 3,900m3 of ore and thus is considerably less efficient than a jet can.
Combo Jet Can Mining
The method is the same as with jetcan mining except that players will work in combo, meaning one member will solely mine while the other solely hauls. This method is very efficient (it can be less profitable if you need to pay for the haul) and it is much harder.
How To Split The ISK
If you are running an op with multiple miners, chances are there are a whole host of different mining ships, each with its different yields based on the mining lasers, the mining crystals in them, ship bonuses, character skills, etc. Moreover, you will also probably have a hauler and even someone providing mining efficiency bonuses. The simplest way to split the ISK return from an op is to clock in the times a player mined for, and then distribute the ISK in proportion to time mined.