Time cheat works here. In case you want to get the Lucky Sling right away set the time ahead on your phone or tablet. When you get your prize, go back to the date and time setting and do it all over again.
There are two colors of peg that you can attach to when you launch yourself upward. The red ones will explode really quickly, and the blue ones will explode after a longer period of time.
Another way to get free coins is to hit the video tab whenever it becomes available and watch a commercial and you will get 25 free coins.