Head kung, iron palm and stuff like that....

I really would like some info on safe methods to develop "iron head", "iron palm" e.t.c...
Especially learning to condision my head, because my head is naturally very hard, i have several exambles with people attacking me and injuring their hands, head, elbow etc on my head.
Other than this i could use some tips on training the fingers safly, i have some problems with my fingers so if you have some sort of very easy and safe fingerstrength and conditioning program i would like to see it.
Thanks in advance.
-Christian.