The HTC One does things a little different than many other Android smartphones. For one, it's only got two buttons -- back and home. It also changes the way it home screens work -- making it a little more difficult to add apps and widgets. Not grossly so; just an extra step or so.
Here's a little tip that'll speed things up a bit. One way to get to the home screen customization section is to long-press on an empty 1x1 spot on a home screen. But what if that home screen is full? You could swipe over to another home screen that has a blank spot, but that's annoying. Or you could pull down the notification bar and go to Settings>Personalize>Customize home screen. Also a pain.
There's a better way. All you have to do is pinch your fingers together on a home screen -- full or not -- and it goes straight to the customization section. From there you can add widgets or apps all you want.
We've got more HTC One tips after the break. Be sure to collect them all!