Porky,
I've been promoting my custom portraits at craft fairs for the past 2-3 years and rarely does someone want a portrait of themselves. 9 out of 10 want one of their kids, grand kids, etc........ but if you have the option of taking a digital photo of those who may be looking for a portrait of themself, then go for it. That way you can preview the shot immediately and take a couple so you'll have options if one doesn't work.
Another thing I've found is that people assume, when I have my saw with me at a show, that I can do a portrait on the spot. I then proceed to tell them that it takes time to create a pattern using a computer which I do at home.
You might want to create a brochure showing some samples of work you've done and your prices along with an order form or instructions on how to place an order. If you can't do that, at minimum, have business cards made up either professionally or on your computer. I would sugest if your budget allows to have them professionally printed in raised ink. You can get a pretty good price at Staples and you can either bring in your own design or use one of their templates. Use spot color and not photographic or colored clip art if having them printed professionally or else they will cost an arm and a leg because they will have to make a different plate for each color. CMYK is very expensive.
Hope this helps!
Linster