I have here listed the dungeons and what you get for myth and soldiery as well as the gear level that drops and the minimum ilvl to get in. You're going to want to run a mix of Brayflox, Halitali, and The Lost City to get your ilvl 70 gear. Sites that I have looked at say all ilvl 70 gear drops from all dungeons but personal experience would tell me otherwise.
I'd prioritize your myth spending into these items first:
Hero's Earring 375
Hero's Ring 375
Bard's Hands 495
Hero's Belt 375
Bard's Tights 825
Bard's Head 495
Try to cap your soldiery two weeks in a row and purchase your:
Weathered Auroral Tabard 825
You will also need 225 myth to get your relic weapon and another 900 to upgrade it. I wouldn't worry too much about upgrading it until you have at least an average ilvl of 70. After you reach ilvl 70 you can start running Coil Turn 1 and we can farm you up some gear from there to help supplement your advancement, but you really don't want to keep anything from Turn 1 so replace it with myth when you can. Turn 2 you can enter at ilvl 73 if you get the head from Turn 2 you can forgo getting your myth head, but the earring that drops in Turn 2 is crap.
While gearing Bard I'd prioritize your stats as follows:
Dex > Acc (to 474) > Crit hit > Det > Sk Sp
You don't really have to worry about the 474 Acc cap yet, that's the cap for Turn 5, but you want to make sure to have enough Acc not to miss in Turn 1 and Turn 2. I'm not sure what there caps are, but if you can enter you should be good.
If you work on all that you'll be geared in no time. Just shoot me or Jamster a message in game if you have any bard related questions.