Provide extra insulation as the most cost effective way of increasing the energy efficiency of the home.
Use joinery types and systems that do not allow thermal bridging.
Use double glazing to reduce heat loss through windows. This will also reduce condensation, mould growth and noise. Well fitting drapes are also very effective in reducing heat loss.
Avoid recessed down lights that require large insulation clearances as these can seriously compromise ceiling insulation. Use other types of lighting or down lights that are specifically designed to allow insulation.