Do not remove the fittings from the bags until you are ready to use them. You may prefer to empty the contents of each bag into a separate container such as an old tobacco tin or similar container as the polythene bags may wear with much use and split. I use small plastic storage drawers. 

  When you use the fittings, it is advisable first to clean up any flash or mould marks. Also file flat some surfaces using fine files and wet & dry sandpaper. Model Slipway has found it helpful to glue half a sheet of wet & dry to a good flat piece of ply (use a contact adhesive or similar)
 

and to rub the fitting onto it. It also helps if you clean up the castings with a brass suede brush. If you brush the fittings well, they will polish up nicely and supply a good finish for painting. Model Slipway has also found that the finish on the fittings is better if they are first sprayed or painted with a matt white or grey.

  When gluing fittings together, or to the model, you can use either thick superglue or a two-part Epoxy resin adhesive. You may please yourself as to which glue you use and when. You may, if you wish, solder the fittings together (if you are good using solder).