A little practise can halp to avoid blue marks. But how to start? Here is a small illustration of the inside of an arm:
![Bild](http://www.fletchers-corner.de/cpg/albums/userpics/10440/oberegliedm.jpg)
As you see the lower part of the arm has two bones, that can be turned against another.
Relaxed the ellbow will take this position:
![Bild](http://www.fletchers-corner.de/cpg/albums/userpics/10440/elb001.jpg)
So try to turn the bones out of the way like this:
![Bild](http://www.fletchers-corner.de/cpg/albums/userpics/10440/elb002.jpg)
Make a mark on your ellbow to help you feel/see what movement will take it out of the way... then practise this movement until it becomes automatic. :-)