All the parts should be washed so the mold release is removed. 
Wash all resin pieces with dishwashing liquid and warm water. 
Rinse thoroughly.

Allow the parts to air dry completely before moving on. 
You can use hair dryer to fasten the drying process.

Resin kits may rarely have small air bubbles in the parts. 
Fill possible air bubble holes with modelling putty. 

Apply a light coat of enamel or lacquer based primer. 
Games Workshop or Tamiya primer will do just fine.
IMPORTANT: Mist (spray very lightly) a light primer coat and let it dry completely (at least15 minutes). Repeat if necessary. Hold the can at least 30 cm from the model.
Problems will occur if the can is held too close during spraying or if too much paint is applied in one coat (loss of details).
It's also a good idea to spray some paint into a small pot and use a brush to paint the parts that are not easily reachable by spray.

Apply paint (feel free to use acrylic colors after priming).