Since there are only 5 slots, you're limited on skill selection to two good ideas: Capture Guru (which works great with capture expert) or Farsight (good for high rank quests [only for baggi+]). A third possible option is to add an Attack Talisman (attack +6, for example) and use attack jewels -- one that takes up 2 slots and four that take up 1 slot each.
In case you want to use this armor to farm Rathian for the Rathian Plate (particularly because of the additional reward with the Capture Expert skill to slightly increase your chances), a good idea is to add 5 Antidote+ gems (you have to farm Gigginox for 5 poison sacs in order to forge these gems). The negate poison skill makes it a lot easier to fight Rathian. I particular you can stay close to its tail to hack it off (e.g. easily with a GS) in order to furtherly increase your chances on a Rathian Plate carve.