A Trusted Aide

 is an unmarked quest in Fallout: New Vegas.

Quick walkthrough

 * Work for Caesar's Legion in order to gain access to Caesar's Legion safehouse.

Detailed walkthrough
Continue doing assigments given by Caesar's Legion members and earn their respect. Once you have reached the status of 'liked', you will be given the key to this safehouse by Lucius, leader of the Praetorian Guard. At this safe house there are multiple sets of legion faction armor and some weapons and the safehouse is made of two rooms connected by stairs.

Normally, completing enough Legion quests to earn 'liked' status involve actions (such as wiping out Camp Forlorn Hope and bombing the NCR monorail at Camp McCarren) that will cause the player to become enemies with the NCR. This can be avoided by simply turning in 50 NCR dogtags to Aurelius of Phoenix or Decanus Severus at Cottonwood Cove to earn 'liked' status with the Legion without angering the NCR (NCR dogtags can be pickpocketed or obtained from NCR troopers killed by random enemies).