Apply salt with no overlapping crystals or mini-piles. A typical parking space should only need a 1/2 cup of salt from a typical coffee mug. If you're not sure, error on using less salt and you can always re-apply if necessary.
Keep salt spreaders away from vegetation: use a shaker in tight spaces.
Avoid applying salt if the temperature is below 15 degrees Fahrenheit: The chemical reaction used to melt ice doesn't occur at this cold temperature, leaving useless salt that may later enter our storm drains. In extreme cold, use sand and sweep it up when it's no longer needed.
Sweep up sand and deicers when the snow and ice have melted. This keeps it out of local surface waters and keeps it from tracking into your home. Both sand and salt can alter aquatic habitat in the long-term.
During the summer, make it a point to fix drainage issues on your property. This avoids the need for applying deicer in the winter.
Keep pets off of salt or cover their feet, as the chemicals can irritate or burn their paws.
Be patient: If you don't see salt on the road, it doesn't mean it hasn't been applied. These products take time to work.
Remember, five pounds less salt applied to the ground saves over 1,000 gallons of water from being polluted.