The amount of PvP actions are so few, I would hope you're able to utilize them optimally without any need for a guide. Apply DoTs -> spam Heavy/Straight combo; weave oGCDs (songs, empyreal, etc.) in between.
Instead, I suspect your issue may be the "sweet spot" distance to shoot at. Too close or too far from your target, and your damage is reduced. See here for more details:
http://forum.square-enix.com/ffxiv/t...ard-and-Archer
Unfortunately, the screenshot they're referring to is no longer present. Maybe someone can point you to a better source of info. I just googled "ffxiv bard pvp distance".
Also, there are the PvP traits "Increased Action Speed" and "Increased Damage Dealt" which you could set to increase your damage if you so desire.
If the ranged "sweet spot" damage reduction was removed a while ago, please let me know. All the info I can find on it is very old.