I haven't used the slime or goop stuff so I can't talk to that. I use something "like" this item:
or:
or:
http://www.autobarn.net/vicv106.html
but I'm sure you can probably pick something up locally.
The kit should include a tool that's kind of like a giant thread needle (but open at the end), a round file with a sharp end for roughening the hole, rubber cement, and several strands of the plug material. The plugs are like very sticky rubber bands about 1/4" (~.6 cm) square by about 3" - 4" (~7 - 10 cm) long. The steps are easy (included in the kit):
1. Find the puncture and remove the obstruction. Mark the hole or stick the file in it.
2. Run the file in and out of the hole to roughen it a little. Note that this takes some force and is why the T-shaped tools are a little easier.
3. Put some rubber cement on the file to coat the hole .
4. Thread a strand of the plug material into the plugging tool so that the eye of the tool is at the midpoint of the plug strand.
5. Coat the plug with rubber cement and stick it into the hole so that "some specified" amount of the 2 ends stick out.
6. Pull the tool out leaving the plug jammed in the hole.
7. Once the glue is dry, cut off the excess with a utility knife.
Have a happy new year!