It's barely possible to make mistakes in the preparation of your ice bong and in the end it all depends on personal taste and preferences.
But here are some tips and suggestions:
# You can put ICE cubes in the water, too.
# If you put your bong in the fridge as a whole before fillig it with water the glass is already cool before filling the bong. But be careful not to freeze your lips on the glass or hurt yourself - the mouthpiece should be warmed up before use.
# If it snows why not use snow in your bong - compressed to little bowls like icecubes or maybe filling up the bong with powdery snow?
# Be aware that as the ice cubes melt the water level rises in your bong - so if your kickhole is quite low it can start to leak through. Thus you should fill in only just enough water in the beginning.
Small hint: you can pimp your ordinary bong to a full icebong using a Ice platform