Check your e-mail or have your parents check theirs for the new Fantage newsletter. Near the bottom it’ll give you some info about WaWaGames. Click the link and register then check your e-mail again and click the validating link. Now log in and click the Rewards button above your username. Now click My Rewards. And put in your Fantage username. You should get 300 free e-coins!
2012 EDIT: Wawagames has changed into Fantagearcade.com <- go there and do some free offers to get eCoins. Also, you can download the Fantage Apps and get free eCoins from there, too. ALSO, you can open up your IDFone and click “earn 20 eCoins”. Watch an ad and then redeem your free eCoins!