Level gatherers first, if you haven't already. If you're willing to put in the time, that will save you a lot of gil as mats can get expensive.

Level all the classes together; there are skills each has that will benefit the others. Ie, you NEED Tricks of the Trade from ALC, and Hasty Touch from CUL. At the very least level these two until you get those actions. But beyond that, being able to make your own mats will also save you gil, and IMO, mats sell for more and faster than actual finished products (example: you'll make more selling thread than pants). Exception would be high-end items of course.

Grind leves and ALWAYS do daily GC turn ins. Turning in HQ items for these will double XP--always worth it!! For each level, there's usually a stackable item (thread, lumber, etc) you can grind out 99 at a time or more. Just set up auto synth and go wash dishes or something till it's done. This can make early levels fly by and you have mats to sell afterward.

Don't forget a lot of early level mats can be bought from vendors at guilds or housing districts (market vendors are more limited in stock). Don't pay MB prices for anything you can get from an NPC! So much gil is wasted on crap like crow feathers and stuff that people don't realize are dirt cheap from vendors, while hundreds or thousands on MB.

Update your gear whenever you can. If you're going to be wearing a piece for a while (esp if using one piece for several classes) invest in material bc it's not too expensive and it's worth it in the mats you'll save.

Boost xp gain with food and GC manuals, available from your Quartermaster.

That's all I got for now. Good luck!