I guess you can call these tips in a way. There may be some spoilers but i have did my best to dimm them down
This game has Random encounters
Keep an eye out for the cards they will always be in the same place these provide permanent stat increases they will appear as a monster and will run first chance they get, so if it did get away exit the area and re enter then head back to the area you fought it.
Watch out for the death monster it can kill you in a certain amount of turns so kill it quick
Take your Time when casting ancient magic you can mess up pretty easy
After Finishing the six kingdoms There will be one doll that you can acquire after defeating a certain boss Enter shadow town and talk to the guy blocking the way. ( id say this doll is one of the best)
The six princess dolls
There will be a crystal Scattered throughout each kingdom as soon as you finish That specific kingdom and get the Sigal you can break these and get that doll
Explore each dungeon carefully you may just find a doll ( i know i did)
Make sure you always have a tomato handy.
(its a revive item)
The puzzles can be really irritating but they will always have a solution
Oh and Once you finish they game the will be a door icon in which you can click to play blackjack