What is the most effective way to get rid of silverfish?
Silverfish like cool, damp locations and feed on paper and other starchy materials.  If the source of your silverfish problem is a crawlspace you might improve things by laying down heavy plastic sheeting over the ground and making sure it's properly vented to reduce moisture a little.  Otherwise, silverfish are very annoying but basically harmless (except to your valuable books/documents- keep them sealed up).