Depends on the tattoo. What they all do is redirect energy from one part of your body to another, so one thing gets stronger but there's always some kind of drawback. That can be anything from increased metabolism to being extra-warm or cold all the time to decreased physical strength or agility. I can't put energy in from the outside.

And I know you didn't say this specifically, but it bears repeating for noobs - I will not try to mess with Trump marks. Pretty sure I couldn't anyway, and I don't want to be on the receiving end when poking one blows up in my face.