A good rental site will offer a selection of plans. Think about how much you’re planning on budgeting for the service. You may want to start out with just one movie rented at a time, and see if an online movie rental service is for you; some people just can't bring themselves to stuff the DVDs in the envelopes and make it to the mailbox everyday. Blockbuster and Netflix both offer free trials, which allow you to try their service for a few weeks—use this time to develop a sense of how many movies you want to rent at a time.Be sure to look at the benefits of each plan offered by a rental site. Some will offer free coupons or more movies per month if you subscribe to a better plan. I've had subscriptions to both Blockbuster.com and Netflix, and Blockbuster had more of these benefits and a lower price. The Blockbuster subscription even got me a coupon for a free used movie from one of their stores.
Shipment speed
If you’re renting online, you probably want to have your movies as quickly as possible. Check the turnaround time of the sites you're looking at. Blockbuster and Netflix were both good in my experience, though Netflix was for some reason generally faster at shipping their movies.
You'll want to make a note of when you have time to watch movies. If you just watch movies on the weekend, it's pretty easy to structure your mailing schedule so that you always have a few DVDs to pop in. If, however, you need a new movie every day, you will require as-fast-as-possible ship times, the biggest movie plan possible, and a budget that accommodates such a plan. A few of my friends have canceled their cable service and use movie rental websites as their sole source of entertainment.