Awesome game! Pro Tip: Use your ears and make a beat out of the sounds your ball makes as he takes the correct path. Learning that beat can help you get though the hardest checkpoints.
I got no tip for endless though, that place was designed by the devil himself :O
2 turtles, healer, shield, 4 goblins, healer, shield, 2 goblins: If you maxed out your stats that combo will get gold on all levels if you use spells right (disable bog towers every wave).