Take more control of Mission Control
If you found Spaces too confusing or too much trouble in Snow Leopard, you should give virtual desktops another try in Lion. Mission Control combines features of Spaces and Exposé and makes them way more usable. A trio of Hints readers have offered up some tips that make Mission Control easier to work with—which could make you more productive.
First, to help you distinguish your virtual desktops from one other, Hints reader simplebeep points out that you can choose a unique desktop picture for each one. Launch System Preferences in your first desktop, go to the Desktop & Screen Saver pane on your first desktop, and set the background image you'd like. Then enter Mission Control (by pressing Control-Up arrow, using the three- or four-finger up-swipe, or clicking on the icon in your Dock). Once you're there, drag the System Preferences window from its current workspace to another desktop. (If you haven't yet created a second desktop, drag it to the ghosted desktop that appears in the upper right corner of Mission Control once you start dragging.) Go to the Desktop & Screen Saver pane again and choose another desktop picture; whatever you choose will appear on that second desktop only. Repeat for as many workspaces as you like. Your separate backgrounds will be saved after you restart.
An anonymous Hints user points out the efficient way to select a different desktop without exiting Mission Control. Say you're in Desktop A and want to drag an app from Desktop B to it. After you launch Mission Control, your instinct might be to click on Desktop B—but that would cause you to immediately exit Mission Control and go to Desktop B. To avoid that, just hold down Option when you click on Desktop B; that will open it within Mission Control.
Finally, Hints reader cibi3d likes the way you can make individual applications appear on specific desktops—or on all desktops or on none: Control-click (right-click) an application's icon in the Dock and look at the Options submenu. There, you can assign which desktops that application should belong to. Assigning it to All Desktops means that it will appear in every workspace; choosing This Desktop while you're in, say, Desktop A will cause that app to appear in that workspace alone. (It's essentially the same as dragging the application's window from another desktop to the current one in Mission Control.)
Clearly Mission Control offers a lot more versatility and power than Spaces of old. If you have other Mission Control hints, please share them in the comments below!