The first decision lies with the type of finish you are after. There are many options – you can render with oxides to obtain a coloured finish, use paint-like products for a smooth finish or apply a textured render.
Whether you will be rendering yourself or have decided to get in a tradesperson, you will need to contact the manufacturer first. They will be able to give you specific advice on the rendering process, how to get the best from their render and what to expect of the finished product.
Once you have decided which product you are going to use you can get started. There are generally two main ways of rendering your fibro home. Option one is to remove all the cover strips of the fibro, place an adhesive base or bonding agent over the fibro and then render it.
The only drawback for this method is there will be no improvement in the thermal insulation for your home.
Your second option is as you suggest, covering the existing fibro with “blueboard” and rendering on top of that. In this case, the blueboard will help to increase your insulation.
As I have mentioned the type of render you go with will determine the process so my advice is to contact the manufacturer and a tradesperson and then go from there.