What are the cons of having tattoos in the U.S. Navy & the U.S. Navy SEALs?

I have not gotten any tattoos yet, but wanted to know whether I should or not as far as rakn advancement, and SEALs would go? I am in DEP U.S. Navy... I ship to boot Jan. 4th, 2010... Advice, and boot suggestions, WELCOME!!! Thank you...