For most sites, you can just leave out the www and it will redirect to www.example.com or just example.com. Twitter, for example, redirects to no www.
Some sites will just accept either (which is a bad idea, actually). A number of really dumb sites will not work without www. Shameful.
And there’s no need to tack on www in front of a subdomain. www.badthing.blogspot.com. www.uncoolbeans.deviantart.com2. Those are bad. The www there adds extra length, looks ugly and is quite certainly unneeded.
Thanks for reading. Tell your friends.
This is the third (second here) in a series of tech posts directed at laymen, non-geeks, etc. Basically a lot of my friends and family.