The 2K I use is mixed in the following ratios but different makes can vary;

Solid colour/direct gloss - 2 parts paint : 1 part hardener + a splash of thinners and a few drops rocket hardener depending on temperature.
Base coats - 1 part paint : 1 part thinners
Lacquer - 2 parts paint : 1 part hardener + a splash of thinners and a few drops of rocket hardener depending on temperature.

Remember the hardener used contains isoynates and you need to use an air fed mask.

Keep away from Cellulose as its out of date and shite!!