I would say over the last 2 years I have done about 75% of my shopping online. The main reason is time. I hate spending my weekends (especially in the summer) stuck indoors. My weeknights are for lots of pup time and hitting the gym. So hence my high rate of online purchasing.
As I think more about shopping online I have really noticed I save more. These days with all of the deal sites, retailmenot has been my most reliable and successful one yet. Every single time I order something online I just Google the name of the store followed by coupons and take a few minutes to test a few, typically I always find one that works!
Another great way to save on online orders is to sign up for emails, they usually always have discounts every few weeks or even a first time purchase discount if you are new to the site!