Tip 1: If you lose a round, you'll lose a heart, and if you lose a heart, it takes fifteen minutes to get it back unless you want to pay coins for it. If you don't want to wait or pay coins, though, go to the date and time menu on your phone and set the time ahead by fifteen minutes per life that you want back, then go back to the game and your lives will be restored. After this, you can set the time back to normal without losing your sped-up lives.
Tip 2: You don't get any kind of bonuses for finishing the levels with more moves left. Every level is a pass or fail, so if you finish with one move left or 5 moves left, you'll get the same reward; all that matters is that you finish the level at all.
Tip 3: The keys will allow you to clean or to rebuild your pool area, or to add new stuff to it. If you tap a key area that lets you build, your main option for what to put into your pool will be free. Your second option will require you to watch an advertisement video, and your third will require you to spend coins in order to get it.
Tip 4: Once you finish rebuilding one area of the park, you'll get to move onto another area. The process will be the same; you'll spend keys in order to clean it up and then spend more keys when you want to add stuff to it. Just remember not to blow all of your coins on the first area; you might want to buy some premium stuff in the second area, too.
Tip 5: Keep on the lookout for new rewards to pop up constantly. If you see a hot air balloon, tap on it. If you have an internet connection, then a video will play. Once the video is done, you can spin the reward wheel, and you'll be able to earn coins, lives, or even boosts such as rockets that you can use in the levels themselves.