First thing tomorrow after you collect everything from overnight write down what your cash is. Tap again as usual and 4 hours later write down what your cash has gone up to. Work out how much you made and spend no more than that building a bunch of KEMs. 4 hours later collect those and build the same amount again - you will earn extra because 1: you get 25% of your KEM spend back when you sell and 2: you get the 6, 8 12 hour buildings etc. income too going into your cash counter.
Those KEMs will help you level up and add sprinkles and the other money will go towards buying buildings and land etc, and eventually on trucks.
Until you get a bonus that you feel helps you earn fast enough spend those donuts only on Burns Boxes or bonus items that work out at 10 donuts for each 1% or less.
As you grow your bonus you'll find you earn more easily and can add more bonus faster
If you're really tempted by any of the premium offerings then for now consider paying real money for the sprinkles and ask yourself is it worth that much to me I'd pay for it -
If no I'd say stick to bonus stuff until you can clear more than 20 donuts a day ( 1,120 in 8 weeks will buy an event and mini-event worth of new content and feed the collider and add to your bonus )
Those are just thoughts, there is no right or wrong way to tap. It's your game to play as you like
