Criminal Connections skill raises your current positive standing with Pirate Factions that is displayed in the Interactions page of your character sheet.
Connections skill raises your current positive standing with Empire Factions that is displayed in the Interactions page of your character sheet.
Diplomacy skill raises your current negative standings displayed in the Interactions page of your character sheet.
That is what the NPC’s look at for access. Having those skills maxed allows you to access agents much faster.
Social skill increases the amount of standing gained for completing missions. That’s the skill you want to have trained up to get max amount of standing gain.
The Social Booster is relatively new, CCP has gifted them to all accounts a couple of times now, usually for Events. There’s 2 different types available. Both work like the Social skill and give a bonus to Agent, Corporation and Faction standing increase. The Social Boosters have an expiration date so check their info before buying them to make sure they’re still active.
Impetus Potency-75 Glamourex Booster
(75% bonus to standing increase)
Impetus Potency-50 Glamourex Booster
(50% bonus to standing increase)
That’s basically it. There’s a few other skills that help as well.
Negotiation skill will increase the amount of ISK payment reward for completing missions.
Agent Divisional skills (Security Connections, Distribution Connections, Mining Connections) will increase the amount of Loyalty Points reward for completing missions.
NOTE: Epic Arcs and other ‘special’ mission offers like Cosmos don’t have LP rewards.