I definitely made mental snap judgements in the past based on outside appearance but I honestly couldn't give a precise example as it easily passed through my mind and corrected myself before making any further judgement on the person. On the other hand, I had experiences where I got judged and it didn't feel alright and had the urge to explain myself while controlling my emotions so I didn't get misunderstood. 

I think some of the practical ways to suspend judgement is to stop, think and understand. When the situation arises where you pass judgement, hold up and ask yourself these several questions "what is my basis of giving judgement?" "what might be the outcome of my judgement?", "is my judgement helping or destructing?" By asking these, you would be able to hold yourself up and suspend your judgements.