I'd strongly advise you not to get a tattoo, for we are commanded not to ink our skin.
"'Do not cut your bodies for the dead or put tattoo marks on yourselves. I am the LORD. -Leviticus 19:28
God expects us to be comfortable in the image he made us in; for it is the very image of God itself. He expects us to be comfortable the way we are and not to make any altercations to our appearances, for this is the way he made us and when we make any altercations to it it is showing God that we have our own preferences to how we want to look and that we don't feel good enough as we are. Not that we should just leave our appearance uncared for and neglected that we allow our facial hair to grow out of control or anything, but we should indeed work with what we have.
And if you're looking for a good way to express your faith and have meaning, leave the mark of Christ on your heart and display that for all to see. Let the glory of Christ be manifested from within you from the inside out. If you remain true to it, the world will ideed see it, for you are called to be the light of the world, and light doesn't shine for itself, but for those who are in the darkness around it to see. It's like wearninfg a cross, you can wear that cross all day even as an expression of faith, but if you do not wear it on the heart, it is absolutely nothing. Let the glory of Christ within you be manifested outwardly through your actions, your deeds, you attitiude, etc. etc., not through anything on your appearance or a tattoo mark.