99% or 100% focus do trick at least 2 levels below current level, seems to work ok, most eco trick is dance in my testing but at higher levels takes longer to gain xp.
lower then 90% focus leads to noticeable nutrio bar consumption, do tricks in the 90%'s, below that stop doing tricks.
make sure you have high affection and high mood to gain max xp when doing tricks.
make sure pet is at least 33% fed before doing tricks for max xp when doing tricks. Below that he starts to get moody and then starts to loose affection.
just a few things I picked up when training pets so far.
Bonus tip: The animal brush at 154% MU will cost 2.88 PED in useage to bring affection to 100% so you can start to gain max xp with tricks faster after capturing a new pet. Alternative is wait a few hours with them spawned before doing tricks to get max xp progression. I have not tested out the advanced animal brush yet still not high enough level to use it.