The best way to get a free hotel room upgrade is to book directly through the hotel, then simply ask if they’d be willing to upgrade you. If it's a special occasion, like a honeymoon or anniversary, let them know and they may give you a complimentary upgrade. You can increase your chances by signing up for their customer loyalty program, branded credit card, or both. You’re also more likely to get an upgrade if you book during the off-season, stay during the week instead of a weekend, and when you check-in later in the day.