Easy money
Enter Barren Earth, the fourth Earth Forest. When you get there inside, at quite few of the Ogre Vines there will be either a Cute Gem or a Lovely Gem which sell for good money.

Easy start
To get an advantage when beginning a new game, choose to take a Fire monster and start in the Earth Forest. By the time you get other monsters, your attacks will be far higher than other wild monsters and you will have an easier ransition no matter what elemental forest you choose.

Boss Fights
When you fight bosses you are fighting one really good guy instead of 3 bad ones. Now when you fight Bosses that are mainly physical (attacks only or mostly), a simple attack can decimate them. You get a speedy earth type with good mana capacity and teach it barrid or barridis then have it cast the spell for the entire battle sheilding your guys and leaving them open for damage. Though DO NOT use this tactic against a boss like Gojet or another boss that cast sleep, poison, or paralysis moves. Hope it works for you if it doesn't that means you guys are either not strong enough, too low mana or don't have enough speed.

Hint
Make sure your beast amulet has a strong beast that knows barridian, one that knows medinite and one that knows that knows tishalite before going to fight levant and lilith and also have some ressurect books, full heal books and sheild bibles handy. if your lucky the fight will only last an hour.

Rare Eggs
Collect Inferno Books and Twill Mugworts from the Fire Tower Forest and buy some Luch Eggs (five is best) from the Kikinak Company. Then, enter the Wind Patina Forest and take a left to the second Ogre Vine. Inside is a plant that merges items. Place the Luch Egg inside, then place the Inferno Book or the Twill Mugwort in. Do not place them in the reversed order or you will not get anything good. Save the game before doing this so you can reset and try again if it does not work the first time.

Water Drac
Defeat Levant in the Dark Forest. Then, Cure will be back to being human. Talk to her and after a little while she will post a job on the work board saying that the reward will be a Drackich (Water Drac). Water Drac cannot be created at item merging