Campaign is pretty slow (unless I'm doing it wrong) I heal, I buff up npc's with earthen ward, thunder spikes, raise where i can. But I've been only capping at 800 or so xp. I use my op credits to do bombing runs at 180 xp each. I'm only at the 3rd medal though (Allied Ribbon) that might be what's hindering my progress.
Melee, and have your avatar melee alongside you. Have it do a few melee BPs, and throw in some magical BPs too. Make sure you take damage, that'll increase exp as well. But don't die. =P
Enfeeble; Paralyze, Slow, anything. If you're /WHM, Paralyze is best for its low cost and low recast. Keep casting it once in a while if whatever you're fighting doesn't have Paralyze.
Raising is great, do it whenever you get the chance. And curing is good, but try to get the most efficient cures you can whenever you get the chance. Carbuncle's Healing Ruby and Healing Ruby II (in the right situation) are very efficient.
Carbuncle's probably one of your best bets for campaign for his ability to stay out long at the least cost, some of the best cures, some relatively cheap buffs, and some pretty decent BP: Rage.
At around your level I generally got my exp up to around 1500-1900 exp in maybe 20-30 mins. I think I might have been capping for the length. It's not the greatest of exp, but it's pretty good and easy. I'm also pretty sure I could have done better if I wasn't capping. I slacked a lot. Also, it gets better as you get access to Spirit Taker at 66 (if your staff is leveled) and Sublimation and Aspir from /SCH at 70 and 74, respectively. If you haven't leveled the /SCH, I'd recommend you do so at least around then. And obviously, better BPs from SMN.
You should try to get your medals up, too. It only takes a few hours every period of 5 days to raise it as fast as possible.
FoV might offer something better, I haven't tried there. But I would suggest maybe a party of 2-3 for best results.