I just started and I'm so lost - Help!

[Erendis]

For leveling other classes you can use hunting log (every class gets separate hunting log), guildleves and fates before level 15, after you reach 15, you can do dungeons. Starting from level 10 you can also do guildhests, they give a large amount of experience once for each class. Do not forget to do low level roulette, as it also gives a lot of experience.

To be able to use Market Board, you have to unlock them through the story quests. If you are already at level 30 story quests, you have unlocked them already. Talk to a retainer vocate at the market in any of city states and hire a retainer. You can hire two free retainers and also can purchase up to two more retainers as a paid service. Use summoning bell in the markets or inn rooms to call your retainer. Retainer can sell your items on MB and is also a big storage space. Gil from sales is stored on retainer.

Also, since you are already level 30, do not forget to get your job by talking to your class guildmaster!