The boosters that are given by spinning the wheel and other free activities. Try to save them and let them collect for use on the harder levels. That way you can get the full effect out of your boosters and win the hard levels without having to keep replaying.
If you do happen to buy boosters, or purchase gold bars there is usually a level in the game on the map, where they will award you with free gold bars and a booster or 2 depending on what you purchased. If anyone who did want to buy some stuff but felt like the package lacks, compared to the price you pay.
Hard levels can be overwhelming but remember it's a game and it's for fun and to pass time. If I find myself stuck on a level I watch YouTube videos to help me with extra tricks and pointers on that particular level. Suzie the Candy Crush Guru is a great one to watch. After watching I try again, if needed I add in…
When I have a level to clear and collect a certain number of chocolate, the first thing I do is look at my board to analyze my first few moves. I want to make specials but not to many that I would clear the board of the machine that generates the chocolate. Get a good number of chocolates on the board but also not to much…
On the levels with multiple objectives (reaching certain a score, clear the board of chocolate, and collect the cherry's) I focus on one objective at a time. It can get kind of tricky to focus on one objective when you only have just a few moves, but it is crucial to win the level.