Nationals of Australia, Canada, the EU, Japan, New Zealand and Switzerland do not need a visa to enter Venezuela, passports are simply stamped upon arrival and bearers may stay for up to 90 days in the country. US and Israeli citizens require visas, and these must be obtained in advance through a Venezuelan embassy abroad. For US citizens tourist visas currently cost US$30, but obtaining them is a headache that involves traveling to a Venezuelan consulate in person. Once issued they are valid for a year, of which 90 days may be spent in Venezuela. For more details see www.eeuu.embajada.gob.ve.
US and Israeli citizens need visas, which must be obtained in advance.