The Mrs and I racked up almost half a million miles last year from signup bonuses, all with minimum spends in the first few months. Not once did we have to do anything other than use the card(s) in question for all of our normal bills and expenses...and paying off each month, obviously.

We first started with any recurring bills being paid from the checking account and switched any and all of them to the credit card if the creditor/company accepted it. I'd bet if you just review your monthly budget you'll find it done quite easily.