You might try looking online for cleaning instructions specific to the make & model you're using…
The blow air / vacumn business is generic and you can try it even if you can't/dont want to open the body. [The couple of wired mice I still have as emergency backups hide the screw to take the body apart under a sticker, if that helps.]
Should probably have asked, but – like the rest – I've been presuming an optical mouse [no track ball on the bottom, just a light]. If, by chance, you are using a mechanical — removing the track ball before using the air trick is recommended. (Also take the oportunity to inspect the transfer wheels as these tend to pick up gunk. )
