Hi, there is very good advice on the posts before.

In my case I tried to not make it a second job or a chore, and since you probably use leves, from time to time I ceased to level the crafters, accumulated leves and rested from the grind. When time passed I recovered the interest on crafting and leveled some more. Many times when I finished a relic quest phase, I turned to level a craft, later focused more on the relic, or leveling a battle class, then again a crafer, etc.

You don't have to be high level to start to make gil, look what items sell quickly and at good profit and make one of it, when it sells make another etc. Usually you will be saving gil until you go back to leveling another craft, that is always an expense you can recover from later.

Sometimes the items you need to turn in for the leves are for sale at the market board and not too expensive, have a look just in case.

In my case I leveled all to 15 (except ARM) soon, then worked towards the class skills I wanted, instead of leveling all at the same pace. The more classes you have, the easier it will be since you can make the mats for one class with the others, many times. For example, if you have a high BSM you can make the HQ ingots for the ARM and getting HQ items will be much easier.

If you don't level all or most classes to 50 you won't be able to craft the most difficult crafts and it will be difficult to obtain HQ, but you can make gil with that level 50 class while you level the others and finally get all the cross-class skills. There are threads that say what cross class skills are needed more urgently.