As I make my way through the levels, can you experienced guys give me a list of items, useful clicks, quests, and zones I should definitely visit?
With as many options as I have, I think it'd be easy to miss some gems without a little guidance.
There's one item (Jann's Veil) I know I definitely want, but it's waaaay out of my reach currently.
Do me a solid, boys. I need a mentor.
As Tuco said, boxing is the way to go if you want to have a decent time going through the expansions. Unless you're dead set on being a Bard, I'd main an SK and have the Bard be backup. Add a Shaman and you can pretty much do anything ,(3x rogue mercs would shred). However SK + Bard would be fine on their own, especially with mercs (one heal, one rogue).
I liked rogue mercs over wizard because rogue mercs generate a lot less aggro; wizard mercs end up tanking unless you make an effort to hold aggro, which is more stress than one needs when tabbing between a couple characters. SK can hold aggro pretty effortlessly against a bard/healer/rogue, less so wizard.
I don't know how good of a mentor I can be when I've forgotten more about the game than I remember at this point. I do remember interesting item quests though.
To add to what others said already, here's stuff to do if you want to "see it all" and slow walk through the game rather than blasting through to the end:
Level 60
-Luclin tradeskill earring (can't remember the name of it - part 1 of the overall tradeskill chain)
-Coldain Shawl quest (pre-req for something later)
Level 65
-Breakdown in Communication (just to have done it and gotten the GoD experience, can solo it up to Qvic and get the initial aug)
-Aid Grimel (tradeskills part 2)
Level 70
-Epic 2.0 (two if boxing an SK - both Bard and SK 2.0s are really really good)
-DODH resist mask (25 missions, so a lot of work, fun though)
-Dragons of Norrath progression (as far as it's doable anyway; Tier 5 is very unnecessary but Tier 1-4 are all great rewards... Tier 1 and 2 can likely be done without any help)
-PoR level 70 auras
Level 75
-Jonas Dagmire's Skeletal Hand (another aug that's good for a little while and involves a bunch of quests, fun to run around doing this, wish the reward were good for longer)
-Direwolf Totem (quest in Icefall Glacier that results in a +3% or so double attack buff that's basically permanent)
Level 80
-Eron's Jewelry (tradeskills, part 3)
-I believe there's a Secrets of Faydwer mega-aug for the face, Steam something or other, that requires doing a ton of missions.
-There's a Faycite Resonance Barrier clicky that is marginally useful and the result of a bunch of other stuff, not really worth going out of your way for
Level 85
-Shawl 2.0 (tradeskills and missions, this one is fun)
-Seeds of Destruction zones have various rewards for doing all their quests, and some of those are good like the one from Old Bloodfields; the end result, Timeshear, really isn't worth it
-Old Man Mackenzie missions are a trio of fun monster missions, probably not worth actually farming for rewards, but do the two Guk missions and the Sol B mission once to have done them, an Enchanter can solo them all
Level 100+
-Shawl 3.0 (might be remembering wrong when you can start doing this one, but it's another missions+tradeskill deal)
-Epic "3.0" weapons (the purple aura shadowy weapons from doing the ROF missions, careful to only get the reward on your main persona because after that it's spent)
-Artisan's Prize (super duper ultra tradeskill quest, uses all the pre-reqs and pretty much everything else)
-Avoid the Alaran Tear quest; it gives you a slot-exclusive stat item for ammo, which adds some Dodge % and something else, but...just don't, it's a grand waste of time
Level 110+
-Burning Lands has four very strong evolving items (IIRC boots, arms, shoulders, ring) that can all drop from the first group mission
-There's a long quest in Torment of Velious to get an even more potent evolving earring
-All of the above can be leveled together as you go