Well, in my opinion the best embrouchure exercises are slurs, chromatic scales, and long tones. I tried the pencil/pen trick for awhile but I didn't feel like I was getting much out of it. If you try building the strength of your embrouchure through practice, you will be able to build your range and begin to develop a good/better tone.
I also don't think you would hurt yourself even if you did the pencil trick every other hour.
