Groups are a wonderful way to organize your model.  It’s also a good way to isolate certain parts of your model and speed up your modeling using the options in Model Info.  Go to Window -> Model Info  -> Components to see the options.  BTW, this will work with either Components or Groups.

If you have multiple occurrences of the same group/component you can choose to fade or hide the others.  The other option is even more important: Fade rest of model.  The Fade control lets you set how well you will see the rest of the model while you are working inside of a group/component.  This is useful to use if you need to use instancing from adjacent points/faces from the surround model outside of your current work space.  Using Hide can be really useful to speed up your work.  Since the rest of the model is hidden when this is checked, SketchUp doesn’t have to be bogged down regenerating the rest of the model while you are working in this group/component.  So it can be useful to break up your model into pieces so you can efficiently do your work.

Another nice thing about setting up groups is when you Zoom Extents, it will center you on just your group/component when you check Hide.  If you have it set to Fade rest of model, it will Zoom Extents to the whole model.  So if you get disoriented when working in your group/component, Zoom Extents can re-orient you.  You can also used the named views (Views ->Toolbars->Views) to get a Top, Iso, or Side view of your group.  Click on the View you want, then Zoom Extents to have the group fill the screen.

Also, to keep from orbiting off to nowhere and loosing track of your group/component, start your orbit over a face.  If you don’t, the orbit will swing wide and you’ll lose track of your place in the larger model. 

To navigate through your group or component sometimes you need to get out of it.  The easiest ways are to Zoom Extents then click beyond the dashed box of the group/component.  The other way is to Pan up and again click outside the dashed box.  The cue to watch for is when you are still inside the box of the group/component the box is light gray.  Once the dash shows up slightly darker, you can select an area outside of the group/component.