Helen - I've been having a play with the blender pen and have found that if you cover the area you are colouring with blender pen before you add the colours, the blender helps keep the inks wetter for longer so they will mix easier than if you colour first then blend on top. though it does make the colours a little lighter and if you put blender pen too near the edges of the image it can encourage the colour to bleed off the image.
COLOURING WITH PROMARKERS #1 - Hair (brunette)
For this "how to.." I have used the Sitting Gorguss Girl image from Sugar Nellie.
How to store and storage