It is so easy to plug a tire. I keep a plug kit in both cars for the unlikely probability that we'll get a flat, but be that as it may, both kits came from sitting in the trunk of previous cars. They don't wear out. They're also relatively cheap. I've seen them for under $20, and they last forever.
I'd also recommend people buy an inexpensive air compressor for filling tires. This may be useful if you're out in the wilderness and your tire has slow-leaked too fast.
Basically, though, if I had a tire that was losing pressure slowly, I'd do the following.
1. Find the leak. This part is easier if you bring the tire pressure up to over 50 lbs. Mix a tiny amount of dish soap in a bowl of water and use a rag to wash it over the tire. Look for a little mountain of bubbles.
2. See if there's something in the hole, and if there is, prepare to remove it by having a strong pair of pliers handy
3. Get plug from plug kit and make sure plug is lubricated, ready to push into the hole, threaded into the Plug Insertion Tool (T-handle with large needle eye)
4. Pull out nail or whatever from hole and quickly use plug tool with plug inserted to push plug into hole. If done correctly, you won't lose any more air.
5. Trim excess plug off. The end of the plug inside the tire will fold down over the hole when you drive and help seal it from the inside even more. It won't hurt if a quarter inch of plug or so lays outside the tire after trimming.
6. Aaaand... Bob's your uncle! Or maybe Steve or Mark. I just don't know your family that well. Your tire should remain leak free until the next nail or until it gets replaced at the end of tread life.
I've plugged many, many tires in trucks I used in my business around construction. Lotsa nails! No way should you have to pull the wheel, dismount the tire, or mess with putting a patch on the inside. Totally unnecessary, but useful if you want to date your tire-man's sister.
I agree with others here that this takes some muscle. Some women can plug a tire, most don't want to mess with it. That's why they invented men, so I hear.