The easiest way to pay these bills is upon receipt. If I'm thumbing through the mail and come across these type of bills, I whip out my check book right then and there. I slap a stamp on the envelope, and put it by the door for mailing. If I set it down on the counter, odds are that I'll forget to pay it. There is nothing more frustrating than getting a late fee on a bill that you had the money to pay for.
So try making it a rule to pay these un-automated bills upon receipt, you'll never be late again.