"Leviticus 19:28: Do not cut your bodies for the dead or put tattoo marks on yourselves. I am the LORD."
There are legitimate reasons for most prohibitions you find in the Bible. Improperly cooked pork and shellfish can be dangerous, if not lethal. In a world without penicillin, tatoos likewise, are dangerous. Why take chances and tempt badness in your life?
Leviticus 19:27 : “Do not cut the hair at the sides of your head or clip off the edges of your beard."
Don't really know the genesis of that one. (no pun intended)
In general, I'm not a fan of tats, but don't really care. I'm personally kind of grateful that the New Testament does away with most of these prohibitions. I can think of few things on this planet that are better than bacon.
Being a sinner, asking for God's mercy, I do not find it useful to condemn others for many things like this. I would condemn homosexuality and similar things because I do not believe such practices are useful for the race, and believe they lead to greater depravity that is dangerous to both the practitioner, and those around them.