As far as gaining CP, you'll want to plow through the storyline of Rhapsody of Vana'diel to get Reisinjima access as I often see good yells for pullers for area damage burning parties (consisting of BST, SMN, and BLU for their high and quick AoE damage). As the puller, you'll just be running around and gathering things up (they will all aggro so no need for ranged attacks like a normal pull) and bringing them to the BST/SMN/BLU (normally with COR for exp roll and WHM or SCH for heals) to slay in one quick blow.
Since that may be new to you, let them know and state you want to start with just 5~10 and work your way up for what you can handle. As far as gear for that kind of job, movement speed + gear and damage reduction gear are priority there. Ask for clarification if any of that doesn't make much sense and I or someone else can clarify.
PLD as a "damage dealer" in a more "standard" type party would want to focus on accuracy, TP gain, and being able to open/close skillchains that black mages can burst on, but the previous mentioned type of party would me much faster. Good luck!
Edit: I know "go through the storyline" doesn't sound fun, but there are bonuses to exp/CP gain to be had, additional trusts (up to 5 for a full "solo" controlled party) and when you first hit 99, you can get into some item level 117/119 stuff via "sparks" and then bayld. Basically no story content (other than obscure annoying missions in WotG where you have to flee around and blow up walls or put shadowbugs on Cait Siths) is tough at all once you get into LV99 item level 117~119 gear.
Sparks gear which you will instantly be able to get into at 99:
https://www.bg-wiki.com/bg/Outrider_Armor_Set
119 stuff you can quickly farm up bayld for in your 117 set (makes your trusts stronger as it will increase your "item level" to 119):
https://www.bg-wiki.com/bg/Gorney_Haubert_%2B1
This guide will get you into much better 119 gear quickly.
https://www.bg-wiki.com/bg/Fresh_99/RoE_Intermediate_Quest/119_Gear_Guide
and with your new 119 item level trusts, you can begin to solo ambuscade (or attempt small groups with friends) to get into this:
https://www.bg-wiki.com/bg/Category:Ambuscade_Rewards#Sulevia.27s_Armor_Sets
and then you can really work from there on reforging your Artifact/Relic/Empyrean armors and start to mix and match sets using the PLD guide from this link that soralin listed in an above reply.
Early shields you'll want to be looking into before you make LV90 Ochain and LV99 Aegis will be, in likely order of obtainment:
https://www.bg-wiki.com/bg/Eminent_Shield
https://www.bg-wiki.com/bg/Homestead_Shield
http://www.bg-wiki.com/bg/Svalinn
http://www.bg-wiki.com/bg/Priwen