If you have friends or have made some new friends, you can form an organization visiting the City Hall. Organizations are very useful for communication and robberies. You can invite other members to you organization using /organizationinvite and you can talk within your organization using /organizationmessage (/om). 

Organization Commands:
/acceptwar (/acwar) - Accepts invitation to a gang war (must be in an organization). This will start a gang war between two organizations.
/convoy (/organizationconvoy, /orgconvoy) - Sets your organization to truck convoy mode.
/crew (/organizationcrew, /orgcrew) - Toggles group crew mode for robberies.
/depositorg (/deporg) - Deposits money to your organization's bank account.
/gangwar (/orgwar, /orggangwar) - Checks gang war information or invite another organization to the gang war.
/organization (/org, /orgmanage)  - Views information about your organization or list all existing ones. Manage your organization if your rank is high enough.
/organizationannounce (/organnounce, /orga) - Makes a group announcement to the members of your organization.
/organizationcall (/orgcall) - Calls particular member or all members of your group to your current location, with optional message. 
/organizationcash (/orgcash, /orgmoney) - Sends money to nearby members (automatically split).
/organizationdrugs (/orgdrugs) - Sends drugs to nearby members (automatically split).
/organizationinvite (/orgi, /orginvite) - Invite another player to your organization.
/organizationjoin (/orgj, /orgjoin, /joinorganization) - Joins or accepts an invitation to an organization.
/organizationmessage (/om, /orgm, /orgmsg, /gm) - Sends a message to your organization.
/organizations (/orgs) - Lists all organizations.
/organizationvoice (/orgv, /orgvoice) - Toggles participation in group-exclusive voice-chat only (on your end).
/withdraworg (/worg) - Withdraw money from the organization's bank account (from the bank or any ATM).

CREWS

If you are a civilian and wish to rob a location as a group, the organization owner can form a crew using /crew. This allows 2-5 players to rob a location together and split the earnings from the robbery. When a crew starts a robbery, all members of the organization will receive a wanted level. Crews are allowed to defend each other from law enforcement agents during the robbery and when the crew is delivering the goods to the final destination. Crews are allowed to defend themselves against law enforcement agents who are actively pursuing them. Crews are NOT allowed to attack law enforcement agents before starting a robbery.