There are several charter airlines that fly directly to Margarita Island International Airport Santiago Mariño.
Germany: Condor Monday, Wednesday, Friday and Sunday (They fly from London Heathrow to Margarita via Germany and Barbados and also direct from Madrid - Spain to Margarita.)
Netherlands: Arkefly, Wednesday
Czech Republic: Czech Airlines, Tuesday and Wednesday
Spain: Air Plus, Monday

There are also flights from Margarita Island to Trinidad and Grenada with the following Venezuelan airlines:

Conviasa, Trinidad and Grenada, daily
Avior, Trinidad, daily
Rutaca, Trinidad (new)

Most of this airlines offer online booking through their homepages - just click on the name of the airline and you will be directed to the main page.

Alitalia: http://www.alitalia.com/ES_ES/home/index.aspx

Air France: http://www.airfrance.com/indexCOM.html

Iberia: http://www.iberia.com/

Lufthansa: http://www.lufthansa.com/es/es/Homepage

American Airlines: http://www.aa.com.ve/homePage.do?locale=es_VE&pref=true

United Airlines: http://www.united.com/