I recommend not buying anything at the first casino. Save all your coins until you get to the second casino and start playing roulette. Here is the tip to get the most coins as fast as possible.
1. Save your game at church near the 2nd casino.
2. If you have more than 1000 coins, go to step 4.
3. Play roulette, betting all your coins to blue/red or even/odd until you have more than 1000 coins (500 is bet limit). If you lose, reset and try again. Once you're done, go back and save.
4. Divide your coins by 42, call that number "LIMIT".
5. Bet each LIMIT like the chart here
http://i29.photobucket.com/albums/c295/ ... table2.gif
Note: In DQ8, there are only 27 numbers, but you get the idea.
6. Now you have about 1/3 chance to hit a big win. If you dont hit it, reset and try again.
7. After a few wins, you'll realize your earnings have multiplied like crazy. Once you are at 500 limit per bet, every time you win, you will earn about 40,000 - 50,000 coins. Every time you win, go back and save.
8. Have fun shopping. Buy that armor for 50,000 coins, it will last you til the end game. The "Falcon Sword" can also be useful.