It's true, tattoos are addictive. I recommend finding a good place and actually start comparing works with other places to get a sense of what makes a good tattoo so you don't end up hating it.
Also, pick a spot out of the way for your first, you'll likely come to dislike your own taste sooner or later so pick a place that doesn't waste valuable tattoo space for later if you decide to get a larger piece.
As for pain, a simple google search will bring up heaps of pain graphs, but most of them are exaggerated. Think about what the pain is like when you pinch the skin as hard as you can in that area and then halve it, that's how much it hurts. It's different for everyone and think about how it would feel to drag a needle through your skin.
You will get there and sit down, they'll start and you'll kick yourself for thinking it was going to be bad because it's actually quite easy to sit through, depending on the location.
As for design, any good artist will want to draw you something original, so get an idea of what you want, bring some reference photos in, draw it yourself even. Probably stray from the cliche infinity symbols and swallows and such.
