if that is the only tattoo you´ll have in a while, then think about what you are usually doing, meaning, how your arm will move and stuff, and how the tattoo is going to look like (I mean this in reference to couple of guitarists/bassists, who have the inner side of the lower arm tattooed, because that is the place most looked in their case, so just to explain what I mean with "movements".)
Also think about how the place is going to look when you are a bit older.
When the whole arm is tattooed, this fact doesn´t really matter, but when you have only one single tattoo, it might still look nice when it has been placed central. =>side of the arm, because the "front" is actually the side....
I guess this is one of the main facts to be considered, if there will be coming up more tattooes around or if it is alone on the place. In the end I´d say the right place for a tattoo feels right. So imagine all possibilities and decide after what feels best.
A good idea could also be, to get the picture with "normal" colour drawn on the spot and then you can think about it for a day, and remove it and start all over again if it feels wrong place.
