Not in cloud above freezing level without de-icing gear...?
Or, if u got da white stuff building up on wings, props etc... go lower! If you cant go lower due lsalts etc you better hope theres a nearby airport with instrument approaches to land at or that whatever your flying has the nuts to get above the cloud!!
Cloud should perhaps include any "VISIBLE MOISTURE"
You don't always have to go lower, you can go higher - just stay out of VISIBLE MOISTURE and you won't ice up, even if "above the freezing level"