An escort is a citizen of the Capitol whose main duty is to accompany the tributes of their assigned district and teach them how to behave properly, and to help them fit in with the guidelines of the Capitol. They have dozens of escort tasks assigned to them around the time of the annual Hunger Games.
Reapings and Victory Tour
Escorts have the honor of calling names for The Hunger Games by choosing names from the female reaping bowl and the male reaping bowl. They are always excited for the Hunger Games on Reaping Day, and are always happy, wishing the children of the districts 'Happy Hunger Games, and may the odds be ever in your favor!' Due to their Capitol upbringing, they don't understand how the people of the districts do not celebrate the Hunger Games, and don't realize how the districts truly fear the Hunger Games.
If the escort's tribute is a victor, the escort's job includes "escorting" the victor on the Victory Tour. After this, the escort may be promoted to a higher ranking district for the next year's games, or they might choose to stay with the district that they were with previously. Effie Trinket wants to be bumped up to a better District where they have real Victors.
She would always make announcements and schedule to prepare and get ready for the day ahead of them. Although Effie cared about her tributes, she never had high hopes for any tributes from District 12 because of their poor living conditions. Effie has very good manners and encourages others to work on them, too (Like Katniss Everdeen).