You should also try to rent from off-airport locations, which tend to be cheaper, especially on the weekends, and pre-pay when you book the rental to get a discount.
What about insurance coverage for your rental? Will the credit card you have give you the coverage you need?
Credit Cards and Car Rental Insurance
All the major cards offer you some form of secondary coverage. If you get in an accident, you file a claim with your auto insurance company and the credit card will cover most extra charges, including deductibles that you need to pay. However, there are many exclusions.