The money talk shouldn't be a 'dreaded' thing at all. It is absolutely fine for you to expect payment for your time and services, and as such is a important part of any business transaction. Any professional would charge for their time. Even if you don't consider yourself a professional - pretend. Conduct yourself as a professional.
Here's a reply that demonstrates this in a professional tone. Just assume that he's willing to pay and tell him how much it will cost.
Dear his name
Thank you for showing interest in my services. I do offer tatoo
designs, and this particular one would cost amount. Usually I charge
percent up front and the rest when the final design is delivered.
You can add in whatever terms you want to use. Consider how many revisions the price includes - things like that.
If you don't know enough about the design he wants, then you can ask him for more detail before giving him a quote. If he is unhappy with the amount, you can negotiate a price in the middle that you are both happy with. If you're just starting out, you can charge less if you want - whatever you feel like.
But don't work for free. You want the client to value you and value your work. What you charge for your work is the value you put on yourself and your time. Giving your work away is saying to the client that your time is worth nothing, and they'll treat you as such. You want them to treat you as a professional and respect you.