Which parts of the Bible do we use as applicable today?

The overall situation with tattoos can be summed up in one question: Which parts of the Bible do we use as applicable today?
Stuff Said/Done by Jesus: Obvious one. But even he often spoke to non-Christians about non-Christian things. The destruction of the Jewish Temple doesn’t entirely apply to us. Is there no benefit? Of course there is benefit. The Bible gives benefit to all people.
Stuff Said/Done by the Apostles/Early Church: Another obvious one. However, there were plenty of cultural issues that aren’t applicable to us today. Is there no benefit? Of course there is benefit. The Bible gives benefit to all people.
Stuff Said/Done by the Prophets: Things get a little more dark here. Most of their purpose was tied up in turning Israel (and other countries) from sin. But here’s another problem. Issues about the Exile and Return of Exile aren’t applicable to us. We’re not in exile. Is there no benefit? Of course there is benefit. The Bible gives benefit to all people.
Stuff said/Done By other people in the Bible: This is the ‘darkest’. The Bible often records someone’s action without approving of it. Even people who followed God wholeheartedly still sinned. You usually have to take application with deep study.
But now we’re back at square one. How do we determine what’s applicable and what’s not when there’s some haziness? I’ve found 4 ways which we can determine if something is applicable to us or not:
1. Our consciences. You don’t need the Bible to condemn murder to know its wrong. All of us have consciences to know what is right and wrong. Some choose to supress and numb their consciences, so Jiminy Cricket can’t be relied on entirely.
2. Biblical Logic. While the Bible may not label something as sinful in an obvious way, it is often general. What I’m saying is this: If every sin through all time was listed, the Bible would be too long to be readable. The Bible covers the “basic stuff” while being general in other areas. For example, how do you know that cutting your wrists is wrong? How do you know that doing drugs is wrong? Know why the Bible says what it says when at all possible.
3. Character of God. The best way to know if something is against God (that is, sinful) is to know God Himself. You can first start out to do this by reading the Bible 100% all the way through. If you do this, you can see God in every outset that he reveals himself. You can learn things about His character that you don’t learn other “normal” places. Secondly, you can strengthen your relationship and become closer to Him. As you do, you will begin to see the things that he approves and disproves of.
4. Our minds. God gave us minds to reason (among other things). When you know God, it’s not hard to see the logic behind his commands. When you see this logic and reasoning, you can begin to apply it in other areas.
So what’s the right answer here? The right answer is: Get as much counsel on hard issues/problems as you can (i.e., do what you’re doing now). If things aren’t obvious, this is what needs to be done.
So what’s my personal opinion? I almost refrain from giving it since others who do not like my answer may disregard the above points [that I think everyone should know]. Nevertheless:
I believe it’s alright, in some contexts. Why?
-Tattooing in the ancient world was different from what it is today.
-Tattoos can now be removed (with enough work)
-Certain kinds of tattoos are very easily removed
Tattoos in the Bible were permanent. They were also non-Godly.
The context: it has to be Christian. A mark on your body, however permanent it may be should have a Christian annotation.
As many of you know, many Christian band members have tattoos. Even though some marks aren’t necessarily Christian, I think they’d offer up a similar reason.