If I can find the hole again, I'll usually glue a patch on it from the inside. I use those giant patches that most kits come with. For cuts that I find on the outside of the tire, I dab some Liquid Nails or RTV on my finger and rub it into the cut.... primarily to keep other debris from working its way in.
BTW... Make it a habit to carry a piece of thin cardboard or a candy bar wrapper in your repair kit. If you ever hit something sharp enough to gash open the tire, you can replace the tube and splint the tire's gash from inside with it... It'll get you home without walking there.
If you're in or around the IT business, see if you can snag a mylar anti-static bag, such as circuit boards are stored in... Those make indestructible tire splints.