In addition to all the other ways to earn miles, you may earn bonus miles when booking a vacation or cruise through your airline's website. The reward miles differ per cruise or vacation package, depending on your class of service, destination, and limited time promotions. The more you travel, the more you earn; so why not maximize all your opportunities!
To the point - Point 9 :
Always remember to log in to your frequent flier account and add your rewards number to any cruise/vacation reservations.