I presume you plan on maining Paladin. Level up Gladiator to Lv.30 and then level up Conjurer to Lv.15. Do the Paladin job quests. Now do the story quests and eventually level up PLD to Lv.50 and if you have Heavensward, get up to Lv.60. Do not worry too much about gear. They give you gear drops from quests, dungeons, and you can purchase gear in towns from NPC shops and market board.

Crafting is a big time and gil investment. Gathering is sort of the same way too. Do not touch these unless you are prepared for the grind involved. If you just want to do battle jobs, you can just focus on those until you make more friends in game to help you out with crafting/gathering.

If you want to level up other battle classes, you get an experience boost if you level classes lower than your main class. So please try not to level up your battle classes equally at the same time. Get one battle class to max level first.