I've been telling people to sign up for a "Frequent Flyer" program for ages , I'm with Emirates and have just got my Gold Card. A couple of trips a year and the miles add up , plus there are usually a few "special offers" like extra miles for booking on-line.
Other factor to consider is that when you get "status" , Silver or Gold , you are much more likely to get upgraded.
Here is my post about this from my trip report.
http://www.phuket-info.com/forums/249264-post38.html