Cleaning dell xps l720x vents

Hi,

I've had some problems with overheating in the past and I want to make sure that I don't run into the same issues with my dell xps l702x. It is about 2 years old now and it does seem to run a little hotter. I don't want to take apart anything but I think that I can at least clean out the vents with a can of compressed air. I'd like to know what's the proper way to do this. My dell xps l702x has three vents at the base and one on the side. Do I just spray all the vents or are some vents not safe to spray? From what I read I know that I should turn off the laptop, unplug the power and remove the battery before proceeding. Is there anything else I should be aware of? What kind/brand of compressed air to use? How far should the can be from the vent during spraying? How should I get at the bottom vents (flip my laptop and spray down into the vents or maybe just put my laptop over the edge and spray up into the vents)? Oh and what is the right way to hold the can because I read that liquid can get into the laptop if the can is not held properly. Any advice is appreciated.

Thanks.