To earn easy money early in the game you have to beat 3 gymleaders and be through the rock tunnel. you will also need a vs. seeker. now go west of lavender town. you will come to a gambler if you beat him he gives you about 2,000 a fight now run 100 steps either back and forth or back to about the poke center and back. set your vs. seeker to select throught the bag. you can also battle the other trainers who are accepting a challenge for some exp. this is a alot of money early in the game to help you start stocking up on balls and potions and such so you have enough whenever you need them.