ok I have 10 years in the pest control industry. I know a little so I will share.
Yes, a pencil size hole will allow a mouse to get through so when rodent proofing make sure you get every hole. Steel wool works well but will rust in humid conditions so use aluminum. Wool size should be 00.
Glue traps will work somwhat but it may gross you out if you are squirmish. Mice may also pull themselves off the glue especially when it is cooler. In bad mouse infestations you will tend to catch younger mice.
Poisons work, however follow the directions closely, and be prepared for a possible smelly situation. Contrary to popular belief, they will not go out "looking for water" and die outside. If anything they will die in the nest where they feel safe.
Traps work quite nice especially the standard "snap" traps. If you have the time, prebait before setting, but you don't have to if you don't want to. The best bait to use is peanut butter. Smear a little ( just a little for scent) around the hole where they are coming where you placed the trap.
There is also a live trap called a Ketch-all that works nice- again use peanut butter inside the trap. The traps are a little pricey compared to snap traps but you can catch them live and release them far outside or release them down the toilet.
I bring a ketch all with me and have a few snap traps. I like to set the ketch all and catch chipmunks and deermice to show the kids and release them later.
Remember, be carefull cleaning up mouse droppings esp. in the southwest. Hanta or Hantu virus can be found in rodent droppings - mouse, chipmunk, pack-rat, deermouse,etc. and
PLEASE PLEASE PLEASE refer to this site for cleanup : http://www.cdc.gov/ncidod/diseases/h.../stc_clean.htm
Coming back from our vacations and sometimes we can bring back little hitchhikers.