If you are having trouble soloing, try leveling up Pugilist to 6 for Second Wind, it restores some HP for nothing at all. You can also equip a wooden wand or staff to level Conjurer for Cure and Protect (you also get both by level 6). Instead of leveling Sub-jobs in this game, you gain new abilities from other classes and specific ones will be useable on other classes. Your abilities menu shows all actions that all classes learn. If it says "All Classes" or "Disciples of War" required, then your archer will be able to use it. Leveling multiple classes for abilities will really help you out and you will find yourself being able to take on much stronger enemies with more abilities.

If you need Level 1 gear or weapons, there are NPCs near the inn in the adventurer's guild in every city that will sell you some for cheap. Aside from that you can pick up some gear from NPCs at the class's guild and in the market wards. If you aren't in Ul'dah, you will probably want to head there since that's where everyone is and where people sell their stuff.

Lastly, for Gathering, this page on the lodestone might help you out. The lodestone Play Guides are pretty helpful and might help answer some questions.