The fastest way to get donuts is to buy them with real currency, dollars, euros, or whatever your country's currency is. Your other option is to farm donuts, which will take a lot of time and tapping, especially if you just starting playing recently. There's a very detailed article over at tstoaddicts that will explain how to farm donuts, just do a search for keyword "KEM" in the search box on that site. It contains the same information that we have been discussing on the forums, but with more charts and graphs. It's a grind to get a donut farming operation going, but it will be worth it in the end, you will never have to hesitate on buying premium characters, buildings, and decorations.