Cleaning The Alienware 18

Hi! I currently have the new alienware 18 with GTX770m SLI. I've had it for almost 5 months now and I'm just curious as to how often should I clean the laptop? and mainly, how do you clean the alienware 18? Do I use an aircan and clean it through outside or should I open the back and clean it there? How should I clean it properly? Thank you for your kind response !