New player

[Kincard]

Basic advice:

1. If you haven't done it yet, there is a tutorial NPC in each nation designed for newer players. You'll get some nice rewards from it designed for newer players.
2. Remember to always get Signet from a gate guard before you head out to kill stuff. Save items you get and sell them on the auction houses. If you wish to increase your Signet duration, you're going to need to run missions for your nation.
3. Look for Fields/Grounds of Valor books, they will increase the xp you gain significantly, and provide gil and tabs. Tabs can be used for some useful bonuses on the battlefield.
3. Gaining levels quickly: These days most people go to Gusgen Mines at level 10 and join the alliances there. They continuously do the skeleton grounds of valor. At level 30 many people go to Crawler's Nest.
4. At level 18, you can unlock a subjob. I'd recommend the Elder Memories quest in Selbina to obtain it. You'll get the Magicked Skull for it while leveling in Gusgen Mines, and the Worm and Apron can be obtained solo safely when you're about level 25. You can ask for help too, of course. Keep your subjob leveled.
5. At level 30, you open up more jobs, but they all require running a quest to obtain.
6. As said above, Mog Sack can make managing your inventory out on the field a lot easier. If you want to make your inventory bigger (this will more or less be required as you get into higher levels), you need to build reputation in Jeuno. You can look it up on the wiki if you want detailed info. The quests to expand your bag are called The Gobbiebag.