There are many approaches.
If you are not so familiar with patent search the easiest way I find is to take one of the found documents on google, e. g. for a virtual reality device:
Then you put this publication no. or the application no. in the Espacenet advanced search:
or use the link directly form google patent search:
For the example you get this result:
Finally you will find CPC classes given for that document:
G02B27/017; A61B5/048; A61B5/11; A61B5/486
Check those for relevance, e. g. you want to find prior art about.
This is where I think you can do a big step to narrow down results for a specific problem or function of what you are interested in.
G02B27/017 [Head mounted] systems with
A61B5/11 [Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb (for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721)]
You can enter those CPC classes in the espacenet search:
The results are only 10: for that search:
You could also search e. g. via key word "virtual reality" directly a matching CPC class, see here:
If you want a reliable full prior-art search you will have to find a professional representative that can help you with this.
Thanks, Matthew. A good point here.
One way to get an idea of the importance of a specific patent publication/application found in the way mentioned above is to check the number of citing documents. That is which other patents or applications cite the currently viewed one.
You can do that in espacenet as well.
From the example above one good result seems to be US2010016730, because it was cited 5 times, see here:
I don't know if the documents can be sorted by number of citing documents. I'll see what I can find.