Try your best to save your money throughout the game. Once you get to Lohgrin and have the lord of the land buy apple gels only and offer them to the lord of the land. Rinse/repeat until they have drop bottles available (3.5 stars I think). Then, buy 15 of them if you can. Stay at an inn which has something like "Deal 5000 damage get 50% more gald". Lohgrin has a "Deal 10000 damage get 75% more gald" with prawns but I think thats much harder to get when you're in your first playthrough. Before you get in a battle with a boss that you know drops gald, set difficulty to simple (this is so you can use all 15 drop bottles in a reasonable time - higher difficulties make you wait longer between item uses) and then enter fight. Use all 15 drop bottles, and do your best to deal enough damage to trigger the bonus gald from the inn food. Once you kill the boss, you should get anywhere from 1.5-2.5 million gald (depending on the boss fought). If you continue to do this for every boss, then you'll have more than enough gald so that you can raise all of your lord of the lands to rank 25, making your new game+ a laughably easy romp through the game even on chaos mode. Bear in mind after earning this much gald, teleporting costs a TON since the price scales with how much gald you have so you'll want to quickly burn that money buying shit and giving it to your lord of the lands over and over again.
Many people say to use the giant mimic treasure chest trick. This works too, but there isn't really a reason to! You can just do it on the normal bosses during the game. I think this trick is for people who are farming gald post-game and already blew the chance to do it on the normal bosses. Also, when you get the point when Simone puts you in an area with no map and no compass late in the game and you end up fighting yourself and one of your seraphs, do this trick for those, especially. On my NG+, I have double-gald x2, the inn 75% bonus, and 30 drop bottles and that fight alone drops over 30 million gald.
