Guild leve inquiries.

Leves are a great way to get SP, but they're better if you have a party to do them with you. Adding more people lets you crank up the difficulty, and you get more SP. You may want to head to Ul'dah and do leves there since it's more populous.

If you look at faction leves you'll notice little totals next to each faction. These faction credits are earned by completing regional leves, and you spend them to take on faction leves. The Brotherhood of the Broken Blade and Azeyma's Shields leves are combat-focused, and typically involve a small boss fight with a bit more story than a battlecraft leve. These typically offer unique items and/or more guild marks than a regular leve as well. The highest tier of these, available at R43 and costing 400 credits per attempt, have about a 50% chance of dropping a runestone, which is the main item required to get the end-game Templar, Buccaneer, or Harlequin gear. The Horn and Hand leves have similar rewards apart from offering none of the end-game gear, but require no combat whatsoever.

I would save as many of your Broken Blade and Shields credits for the 400-credit leves, as many of their rewards still cost several million gil. Another rare item to look out for in faction leves is the Vintage Jester's Cap, which is also valuable. Feel free to spend your Horn and Hand credits on leves that offer items you need or want, or even just for the guild marks. Keep in mind that the credits for each faction caps at 1000, so spend them when you get close to that point so they don't go to waste.