Tutorial for adding real Tattoo on face
take the image in photoshop to edit and make it black-white.
(I took one of the image from Google)
Crop the image so that object is in the middle.
Adjust the image's brightness using curves (Ctrl + M) and Level(Ctrl + L).
Burn the shadows of the image by burn tool. (Keep Range=Shadows and Exposure=15-20).
Create new blank layer (ctrl+shft+n), name it 'layer1'.
Now select Brush tool and the tattoo brush of your choice. Click on the layer, where you want a tattoo.
(f you don't have Tattoo brush set, the download the set and copy it in to Adobe --> ps--> presets --> brushes).
Now make a duplicate layer of the 'layer1' by right clicking on the layer (Ctrl+J).
the name of the layer is 'layer1 copy'.
Set the property of the 'layer1' to overly 88%,
Set the property of the 'layer1 copy' to soft light 70%.
Same like this you can add more tattoos..
create new layer(ctrl+shft+n) name it 'layer2'
select the another brush and set the position of tattoo.
Make a duplicate layer of it.. name will be 'layer2 copy'.
set 'layer2' property to overly 88%, and 'layer2 copy' property to soft light 70%;
You will get the final real tattoo.