Updated Mon, Feb 15, 2010 by Space Junkie
The most typical grind is to run missions to get standings high enough to run level 4 missions for a particular corporation, and then to farm that corporation's level four missions for valuable rewards. Level 4 missions are the highest level of mission that can be run effectively by a single character and still be profitable given the time spent. Though level 5 missions exist, they are designed to be run by several people at once, reducing each person's share of loot to the point where they would usually be better off running level 4 missions.
Why Grind Missions?
Pilots grind missions to increase their standings, to get mission rewards, to accrue loyalty points that may be spent at that corporation's loyalty point store, to pick up loot and salvage wrecks during the course of the missions, and to gain access to perks that come with high corporation or faction standings. Also, special bonuses are sometimes possible within higher-level missions. These take the form of extra acceleration gate that can only be entered if a semi-expensive item is expended. In such cases, the room usually contains a valuable bonus of some kind.
In order to run missions for an agent, you must have high enough standings with that agent. The higher that agent's level and quality level, the higher your standings need to be. Getting these standings is the basis of the grind.
The Traditional Grind
Whenever you kill an NPC, your standings decrease to that NPC's corporation and faction, and increase among that faction's enemies. For example, if you kill an NPC belonging to the angel cartel, your standings to the Angel Cartel will lower, but standings with the Minmatar Rebublic will raise. There may also be secondary benefits. Allies of the Minmatar Republic will improve their standings, though to a lesser extent, and enemies of the Minmatar Republic may decrease their standings to you, though this will also be to a lesser extent.
A more rapid change in corporate standings will occur if missions are run for a corporation. These missions will typically also involve shooting the enemies of the corporation issuing the mission, further improving your standings gains as you run them.
Every sixteen missions that you run, a storyline mission will be offered by a random agent belonging to that faction. When completed, that mission will drastically improve your standing with the corporation that offered the mission, but also significantly increasing your faction standing. For this reason, storyline missions are the most important part of grinding missions for standing.
Agent Standings Versus Corporate Standings Versus Faction Standings
As you run missions for an agent, your standings with him in particular will improve fairly quickly. Your standings to that agent's corporation will also improve, though at a much slower rate. Finally, when you run storyline missions, your standings with the faction to which that agent belongs will improve.
If your faction standings are higher than your corporate standings, they will be used to see if that agent is willing to talk to you. Because faction standings affect so many more agents, they are more desirable.
To be absolutely clear: Agent standings are with a single agent, e.g. Karde Romu, and improve as you run missions for that agent. Corporate standings are with a specific NPC corporation, e.g. Ministry of Internal Order, and change as you run missions for any agents in that corporation. Faction standings are with the larger NPC factions, e.g. Amarr, within which are many corporations, and change slightly as you run missions in general, but change dramatically as you run storyline missions.