I don't play on PS3, but I can tell you that these are the abilities you'll want the most immediate access to: Fast Blade, Savage Blade, Rage of Halone, Shield Lob, Fight or Flight, Shield Oath, Sword Oath, Provoke, Spirits Within, and Circle of Scorn. FB/SB/RoH should be the easiest to access, as Anubis mentioned, then Provoke/Shield Lob/Fight or Flight should all be near eachother, along with SW and CoS. Shield Oath and Sword Oath are your Tank stance and DPS stance respectively, so being able to switch between the two will be important at end game. Cooldowns should fill the rest of the slots, along with Cover and Stoneskin. Not actually sure how much room the PS3 hotbar has as there are a lot of abilities, but most PS3 players I know find it intuitive after awhile, so try not to stress if things seem hard right away. It all comes down to muscle memory. Good luck!

E: Forgot about Flash. Probably a pretty high priority similar to your RoH combo as it is your only GCD AOE move. Riot Blade should probably be somewhere as well... man, PLD is really simple to play but you never realize how many buttons you use on the regular until you have to map 'em all out.