For my site I have the following htaccess rules:
# BEGIN Gzip
AddOutputFilterByType DEFLATE text/text text/html text/plain tex
In my case, I change a lot an specific JS file and I need it to be in its last version in all browsers where is being used.
I do not have a specific version number for this file, so I simply hash the current date and time (hour and minute) and pass it as the version number:
I need it to be loaded every minute, but you can decide when it should be reloaded.