In order to get any satisfactory result in odour removal as much as the contaminant as possible needs to be removed from the surfaces. In this instance, washing down with a high alkaline detergent (such as Craftex Champion or Prochem Ultrapac Renovate) will remove the remnants of the nicotine and associated oils. However, even this is not a complete answer as paint is basically plastic and plastics readily absorb odours. In view of this in incidents of heavy odour contamination a suitable sealant is required before redecoration. One of the most effective and easiest to apply is Chemspec's Fix Soot. Once this has dried the walls can be painted as normal. Be aware that nicotine odours permeate every surface and all the soft furnishings, kitchen units, carpets etc will be holding odour and also need to be cleaned.