Some bills are going to be the same amount every time they arrive in the mail. Rent or mortgage payments and insurance payments should remain constant over time. Your bank or credit union may have an automatic payment feature that will allow you to set up a payment from your account on the same date each month.
Many banks and credit unions will let you create an automatic bill payment process online. You'll need to log in to your financial institution's Web site and set up the details for each account. The site will likely ask you for information like your account numbers and the billing address for each bill.
Some utility companies offer an automatic payment option that will deduct your monthly bill directly from a bank account or credit card of your choice. These options require you to share account information with an outside party. For that reason, you may wish to create a bank account specifically to cover the cost of monthly bills and use your primary account for other banking needs.