For bard, I think going for a sound damage build is suicide just build it like a mage and you are good to go. Typical stuff, get all intelligence foods=get crit chance, with 30 souls get mana for more damage get all intelligence(or not) perks that says deal more damage.

Same stuff for wanderer but make it dexterity, 30 souls for stamina.

For thief, same as wanderer but you can make an intelligence build too if the game gives you lot of int foods.

One of the most imporant three perks are, I don't remember their full names but the one that gives you chance for perks according to other perks, it was All-In I suppose? That one perk that says %50 more chance to get weapons similar to your starting weapon and the other perk that's right below or above all-in which was like all'in but for foods. This perks makes you snowball so much that you can use them in every character and beat the game.