Similar situation here - must be the age (DD is 2.5 yo)....

We pretty much have a routine (dinner, bath/shower, pjs on, milk, quiet time, brush teeth, bed & sometimes a book (depends if DD wants one read or not) etc... but one thing we are constantly doing is telling DD 'in 30 mins it is bedtime, in 15 mins it is bedtime' then 'in 10 mins it is bedtime' and so on.... so she knows that bedtime is coming. Sometimes she'll argue, other times she is ok with it. Depends on her mood.

Another thing we did was to say to DD that we will shut the door if she didn't stay in her bed. Sometimes, no problem, but other times she would be up and then we'd put her back to bed & shut the door. She'd throw the biggest tantrum, I'd give her a little time and then carefully (she was usually right up against the door) open the door & reiterate why we shut the door and tell her that if she doesn't stay in bed, the door will be shut again. Usually only need to do it once & then she won't try it again.

GL. Some great tips from the other ladies