Simply put, you try not to. If the runway is long enough, you often find that you can't use it because crosswind limitation due poor braking action. The other "gotcha" that often arises is that the crews who sweep the runways not instructed to clean a width insufficient for operations. Not so long ago I was offered a swept runway with a good braking action (nice of them to test it!). Shame the width was only 15M and the swept snow was banked just beyond the cleared strip.
Generally though, if you go to somewhere like Sweden, Norway, Finland, Latvia etc. where they are used to snow, contamination isn't a problem. Their runways are swept properly and you can operate. Obviously if snow is falling or forecast, having a cast iron alternate is a "good thing" - especially one which you can use with a crosswind restriction due poor BA. In the UK though, the calendar method of flight planning is preferable. Choose a different date to fly.
PM