Tell us where your from (in the game), and we can provide more specific help.
At the start of the game, the NPC stores can be a lot cheaper than buying equipment from the Auction House (AH), but later on, they tend to be very expensive. Really, it pays to shop around to get the best value.
Additionally, you do start with a basic ‘Onion’ brand weapon in your inventory, which isn’t equipped by default. What this weapon is depends on your starting Job:
Warrior (WAR): Onion Sword
Thief (THF): Onion Knife
Monk (MNK): none (see below)
White Mage (WHM): Onion Rod
Black Mage (BLM): Onion Staff
Red Mage (RDM): Onion Dagger
Incidentally, if you start as a Monk, you do not start with a weapon, as Monks are masters of unarmed, hand-to-hand combat. However, they do start with a White Belt waist item in their inventory, which boosts STR by a small amount to compensate for the lack of a weapon.
It may seem trivial, but a lot of new players rush into battle without even knowing they have a starting weapon to equip, and consequently find it a lot tougher than it should be. So don’t forget to equip your weapon before fighting. The starting weapon is satisfactory for the first couple of levels, but it does start to get a little underpowered as you level up.
For money, just sell crystals. You can also try getting a little money selling rabbit skins or bat wings and the like. Anything you find, sell. Eventually progress into La Theine Plateau at lvl 10ish (depending on job, mages possibly a bit later to be safe), and at lvl 10-12 start looking for a party in Valkurm Dunes, to the south of La Theine Plateau.
Also, when you begin partying with people for experience, try to set up a party with people that can perform these jobs:
Healer: Almost always a White Mage, but if one isn’t available you can go for a Red Mage, subbing White Mage if possible. Sometimes a Bard or Summoner who is subbing White Mage can do the trick, but it’d not advisable.
Tank: At this level, Warrior. Basically all this person does it take damage, so the Provoke ability is a must, any job that can provoke works. Later on Ninja does pretty well, and so does Paladin. But for now, in the dunes, just make sure the tank can provoke, keep the attention of the mob on him/herself, and recieve continual healing.
Puller: This person’s job is finding the monsters. The party will generally stay in one area that’s safe, called a camp, and this person will go out and "pull" monsters (one at a time =P) into the camp. Theif works well, as does Ranger. Any job that can perfrom a ranged attack and perferably be able to take damge works.
Damage Dealers (DD): These are a must, Black Mages, Dark Knights, Warriors, Samurai, Dragoon’s, Theives, etc. are good. Most jobs are DD jobs. What qualifies a job as a DD job? It’s any job that’s duty is to deal damge (magical or physical) to the enemy, but not to tank or pull. You’ll want a few of these, 2 is sufficient but 3 is nice, if you can’t find the next job.
Buffer/Debuffer: Not so critical at your level, but certainly at later levels. This is almost always Red Mage, but Bard, (probably Dancer, I dunno though, just really came out today =P) Corsair, and White Mage also can buff/debuff. Keep this in mind for higher levels.
In summary, you need someone who can take the heat of the monster, someone to heal that person, someone to get new monsters and people to kill the monster you already have. If you can remember those things you should be fine.