Leinster lost their Heineken Cup title after back-to-back defeats to beaten finalists ASM Clermont Auvergne last time out and Cullen is keen to avoid a repeat this season.
Just making it through to the last eight won't be easy, though, after Cullen and co were drawn against French Champions Castres Olympique, four-times Celtic kings the Ospreys and high-flying Northampton Saints, the side Leinster beat to claim the second of their Heineken Cup triumphs in 2011.
"We didn't manage to get out of our pool last season when we got beaten by Clermont twice, so we're going to have to be a bit smarter this time as we try to navigate our way towards the knockout stage," said Cullen.
"There's no great point saying that it's a really tough pool, because that's the way it always is. The three clubs we're up against in Pool 1 have shown some very decent recent form.
"It's true that in the past that you got the feeling from Castres that they weren't always prioritising Europe, but they have that French title under their belt now and they might now be focusing more on the Heineken Cup. We've got them at home in Round 2, so we'll know pretty quickly what their mood is.
"Northampton Saints have made some really good signings. For me, Kahn Fotulai'i was there or thereabouts as the best player in the PRO12 last season, we know that George North is a phenomenal athlete and everyone is now aware of what he's capable of doing. They've also got Alex Corbisiero and, perhaps more importantly, they have good continuity in their coaching set-up, so Northampton will be a serious challenge for us.
"The Ospreys are the form team in the RaboDirect PRO12… they have a hell of a lot of quality in their squad. They were at the heart of the Lions pack, they have a good flow of young Welsh players coming through, and we're acutely aware that we'll have to be on our game to get something out of that first weekend at the Liberty Stadium."
Cullen won't be leading from the front at the Liberty a week on Saturday, though, as he continues his recovery from an Achilles operation.
The former Ireland and Leicester lock could remain sidelined until the end of the month, meaning he won't make the squad for that Welsh trip or the following week's clash with Castres at the RDS.
"I don't have a date at the moment," added Cullen in relation to his return to action.
"I'm not running yet. I'm getting closer all the time, I'm getting there slowly but surely."