An easy way to finish the Mythos of Marge level is by standing in the ash tray and waiting for the dragon to return there. Punch it while it is inside the ash tray and you will not be harmed by the fire because there is an invisible shield in the ash tray.
Get all the Duff Beer Caps, Krusty Koupons, Marge's Coupons, and Malibou Stacy Cards to unlock items for Pet Homer and Clichés. Note: You can go back to previous levels to use new powers you have unlocked. Also, in first level ("Chocolate Land"), go to the Simpson's house and tap the thought bubble.
Unlock the following clichés by performing the corresponding tasks:
CLICHE - HOW TO UNLOCK Invisible Wall - In the "Mythos Of Marge" level, on the cigarette nest jump to left and get very close to the wall. Chasm Death - In the "Bartman Begins" level, when you get to the gargoyle head do not press the button. Run over the edge. Water Warp - In "The Land Of Chocolate" level, when you get to the bourbon biscuits have a swim in the liquid chocolate. Double Jump - In "The Land Of Chocolate" level, simply double jump.