As a healer, War are a bit harder to heal if the player doesnt manage their overpower (to keep everyone else from getting emnity) and their self-heal abilities. Pld, however dont get hit as much do to sheild/block-rate, though also have its own issues (as it has flash for an aoe emnity gain on mana--when its out its either ether or zerg)

as a War you will probably want to get gld to 34 for the cross class skill. you may want to work on PGL/MNK to get fleetfoot(4), second wind (8)and if ambitious Mantra (42)
As a Pld you will probably want to get mrd to 26 for the cross class skill. You may want to level CNJ/WHM to get protect (8) and Stoneskin (34)

but really its all down to what you want to play, and the style. Warriors are built as a aoe/self-heal or bust tank and Paladin is built to take a bit more hits, but can loose emnity fast if the enemies aren't marked for their order.
As to dragoon, I'd still work on it. Be it after something else gets to 50, and you get the xp bonus for second class, or when you dont wanna tank (if your not working on classes for skills)
Good Luck!