Examine your dates. If they are flexible, you will be more likely to find inexpensive car rental rates. For example, it's generally cheaper to rent a car for a week than it is to rent a car for a day or two. This is especially relevant in touristy areas such as Orlando.
Generally speaking, there is no particular day of the week that results in lower car rental rates than another, but in Orlando, many people arrive on Friday and Saturday for their vacations, so you might save a few dollars if you pick up your rental on a Tuesday or Wednesday.
Check the Internet. There are many sites that offer links to the best deals currently available from each site. Instead of checking each travel and car-rental site, for example, these sites might link you directly to some of the best current deals. Sites like Smarter Travel can link you to the best deals and help you determine if you qualify (by highlighting which of the deals require an automobile or warehouse club membership, for example).
If you don't turn up a suitable deal that way, go to each of the car rental websites directly. This can be a bit more time consuming, but you might turn up an unexpected --- and excellent --- deal this way.
Think about any other discounts for which you might be eligible. Do you belong to a trade association or a professional association that offers travel discounts? Look into anything you think might provide you with a discount.
If you have not booked your vacation package to Orlando yet, you might consider rolling your rental car expense into a full vacation package. Often, the rental car only adds a few dollars a day to a vacation package, yet will be significantly more if you book it separately from your vacation package.
If you are booking your rental car last minute, consider Hotwire. While you won't know which car rental company you're renting with until after you book, you can realize significant savings on your Orlando car rental using a site such as Hotwire or Priceline, where you can name your own price and often score deep discounts.
Peak season in Orlando can mean too many visitors and too few discounted car rental rates, but it can also mean big discounts if visitors are renting minivans and you're willing to rent a compact.