welcome to my world!! we have twins age 2-and have been successful to a point. They have been out of their beds since 18 months.
Most of is establishing a routine, and keeping to it. we let them grab a book or a toy to look at when they go down for a nap, and then I sit in the rocker with a book for myself. They quite down and go to sleep usually right away, though many days it can take up to 45 min. Currently, they have been really good about getting quiet then going to sleep.
HOWEVER, if I leave the room before they are totally asleep, even though one eyelid is closed and the other on its way, they are up and running amok.Same for the evening, but I add storytime to the mix.
Additionaly, if they are up after 1 warning, they lose the coveted toy or book for the rest of the day. Once they realize that, it works rather well.
Good luck, it takes patience and preserverence, but eventually, they get it.