I am getting better but still probably don't say as often as I should. I let me feet do the talking alot though- if I get bad service I don't go back if I can help it.
I also try to let the company know if I get good service- we were pretty happy with the service Qantas gave us, especially when we were booking the tickets as our bank mucked them around so much so I sent them and email saying thanks. Got a really nice one back too

I know when I was in retail it always gave me warm fuzzies when we got good feedback so I try to do the same when I'm happy with service.