Can good hygiene prevent parasites?

Depends: This depends on the parasite. Some parasites are through fecal to oral transmission, some are through foods and ingestions that have nothing to do with hygiene. Good hygiene can certainly help prevent some parasites, but not all.

It helps a little: You can always shake the wrong hand, but while nothing can absolutely prevent you picking something up staying clean can't hurt. But you'll be eating and more parasites are food born than spread through poor hygeine.