Adrian Gosling (http://www.speedlinemodels.co.uk/)

Adrian suggests using a product called Plast 'X' 4 from U-POL . It comes in 400 ml aerosol cans and can be found in two different textures, fine (Plast 'X' 4F) and coarse (Plast 'X' 4C). The product is normally used for fixing plastic car bumpers.

Here are a few useful links:

U-POL homepage

Plast 'X' paint

Plast 'X' paint technical data sheet

Clive Lawford

This is an easy one!

I just use wet and dry paper choosing the grad, which matches the scale best.