Sometimes I want to shrink or compact a project ("dead" bars or intros too long, etc). Which way is the easiest? I just use "ctrl a" and mark the bars I want to delete on the time ruler and press "delete", the hole is filled by marking the clips on the right side of this hole. Is this the easiest way? I found problems with clips getting in the wrong position by doing this. Can't I delete the itself in some way or another?

To delete silence, just drag the clips closer to each other. This makes the silience shorter. 
Make sure to set your snap to grid. there are other ways, but i like this way.

Cj

Thanks CJ!

Your welcome. You can move any clip in sonar. Just because its recorded in that area doesn't mean it has to stay there.