The men from Llanelli are searching for a second straight title when they travel to the Aviva Stadium on Saturday.
Scarlets were beaten comfortably by Leinster at the Aviva at the semi-final stage of the Champions Cup earlier this season, but things are expected to be closer this time around.
“I’m sure Scarlets would have learned a few lessons from that day about how they managed the ball and the speed of our ball,” said Cullen as he looked back on the European clash between the sides.
“Once they have a lead they are so difficult to play against because they have so many men defending in the front line, they’re very aggressive at the ruck, and they make life very uncomfortable for teams.
“They had 21 points in the first half against us last year and you can see the quality they have. They’re very dangerous in terms of taking the chances they have when they come along.
“They’re very, very good at taking them, very good in terms of their skill set, and they execute the opportunities they get. They go hard at the breakdown and against Glasgow they looked very, very strong once again.”
Leinster have been boosted on the injury front ahead of the final.
Star men Johnny Sexton, Isa Nacewa, Rob Kearney and Dan Leavy are all in contention to be involved after knocks, while centre Robbie Henshaw has an outside chance of making the game.
“A fast start is huge in finals, it’s massive. You have to make sure you manage the start of games well so you’re not trying to play catch up,” said Cullen.
“Scarlets are very good at that and they taught us a lesson in the PRO12 semi-final last year. In the final against Munster they were incredibly clinical.
“We’ve seen it time and time again this season when they come out of the blocks very quickly and they’re a very hard team to play catch up against.
“How we manage to start the game will be hugely important. For us this is the game, it’s the one we’ve been working towards all season and it’s time we deliver now.
“We have to recover and prepare well as best as we possibly can and give ourselves the best chance going into the game.
“Both teams know each other very, very well so the little details will be vitally important.”
