Make sure you save the game every time you do something in the game.
Equip the weapons, armor, or accesories as soon as you get them. Also use flowers tabs, flower jars, and flower boxes as soon as you get them.
Take some time in areas that have bad guys in them to train your people up a few levels. It will make the game a lot easier to get through.
Make sure you use "timed hits" to increase the damage you deal and "timed blocks" to decrease the damage delt to you.(see the characters profile pages to learn their timed moves)
Be sure to buy all the new weapons and armor when you come to new shop.
Always have a lot of mushrooms and pick me ups with you just incase you meet a dangerous foe.
ADVANCED TIPS:
In the forest maze you can jump on top of the catipilars to get coins. If you jump on one 10 times in a row you will get a frog coin.
In Seaside Town there is a frog that will sell you stuff for frog coins. Buy "Coin Trick" from him. Coin Trick doubles the amount of coins you recieve from a battle.
If you use Geno on your team using his "Geno Whirl" can deal up to 9,999 damage. Wait until the yellow beam goes through the foe. Press y right before the damage count is shown.(this won't work on bosses)
Use the chest that Magikoopa makes for you in bowsers keep to get infanite coins.
Make sure you go back to the midas river course. There's a good chance you missed some frog coins on your first try and the normal coins keep coming back.
A good combination if you have Princess on your team is to have lazy shell equiped to mario and have princess heal your team with group hug.
First you go to Boosters Tower and there is a guy that wants you to play a game where you guess which hand has the yellow ball. You play that game many many times until you get a bright card. Then you go to Bean Valley. You will find a Shy Away watering plants. In one of them there is a gold Chomp, beat him and jump around there a LOT! A block will apear. Jump on it and go threw the path. On the map Great Guys Casino will apear. There Great Guy will want You to play a game which is where you have to look a way. Play that game many many times and he will give you a Star Egg. It is kind of like Rock Candy But it is infinite but it takes away less lives.
Get the B'tub ring and Mystery Egg. Put the B'tub ring on toadstool and fight a battle. Use the Mystery Egg 10 times and it will give you Lambs Lure.
After you beat Booster, go to the inn. Talk to the kid there. Keep on talking to him and he will sell you his Game Boy for 500 gold coins. Buy it, and you can play Beetle Mania, on the menu. There are a total of three different backgrounds, and they appear in different lands.
Buy fireworks from the Mole in Moleville, and trade it for a Shiny Stone, from the little girl. Use the Shiny Stone on the Sealed door in Monstro Town, and it will open. Inside is a Final Fantasy boss called Culex. Beat him and he will give you the Quartz Gem. Equip it on Geno, and you will see a red star in the next battle. Just when the star disappears, press Y. You'll cast a super lightning bolt on all enemies.
At the sand pits leading to the monster Village, jump 3 consecutive times on the Shogun's head without touching the ground for a free frog coin.
Grate Guys Casino: First you need a Bright Card. You can get a Bright Card in Boosters Tower, by talking to knife guy and playing 30 games with him... you have to win each one. If you mess up, you can start over. After you get the card, go to Bean Valley. Keep going where there's ways to go until you find a big place with a bunch of pipes. Phiranah plants are in them. Go to the last one, fight the Pihranah plant in it, go in it, kill the Chomp in the left hand corner of the room. Go where it was standing and jump 3 times. A floating block should appear. Jump on it, and then leap to the top of the wall and go where that path beginning thing leads and to your left should be Grate Guy Casino.
Play the "Dealer" at the casino in cards to win frog coins.
Use goddie bags on weak foes over and over to earn coins.