Depends on what your gonna do, i'd highly recommend this.
Level 1-37 ( Stick to Main Quests ) Any Class Recommended
Level 37-39 ( Grind Level 37 Guild Quest - Loto Crisis: Food Alert, can be purchased in Guild Towns at the Board or at Kaiser in Aven ) Bard Recommended
Level 39-41 ( Do Barasms Chasms + GuildQuests - Warning: Barasms Chasms, can be purchased in Guild Towns at the Board ) Bard, Tank & DPS Recommended
Level 41-45 ( Do Level 41 GQ's Until level 45 - Golden City Alert: Soldiers Needed, can be found in Guild Towns at the Board or in Aven at Kaiser ) Bard HIGHLY Recommended
Level 45-50 ( Get The Following Items from the Following Fame chests, thereafter grind the first room in Veninfang by Kiting all the mobs )
: Magic Fiddle ( Approx 15 Gold and can be purchased in the Auction House )
: Heirloom Ring ( Approx 50 Gold from Valley Of Kings - Fame Chest )
: Screaming Ring ( Approx 6 Gold from Goss Mountains - Fame Chest )
: Glider Cape ( Approx 20 Gold from Wetlands - Fame Chest )
Bard & Mage HIGHLY Recommended
I'd say focus on Bard overall in the game and join random parties along your way.