That can depend on personal beliefs, but there are some that I know of. The cross used on firefighters symbols or the Maltese Cross are used as a symbol of protection.This is a Maltese cross.
http://www.learnnc.org/lp/media/uploads/2007/08/maltese_cross.jpg There are some symbols that I am unsure of the name but i know that they stand for protection, easiest way to find a symbol for protection is to type that in to a search engine and look at the images. As far as the symbol it would depend heavily on your personal beliefs and taste.
the Celtic knot'
A Fu Dog Tattoo symbolizes protection from harmful influences and people with evil intentions.
One tattoo that symbolizes transformation is the butterfly. Another tattoo that also represents transformation is the lotus flower which represents beauty.
A dagger tattoo symbolizes death.
dragons!!!!
yes
A tattoo crown symbolizes authority and loyalty
Tattoo saying MIRACLE
A tattoo crown symbolizes authority and loyalty
yin yang
Clouds !
DICE