- Be realistic. A £20,000 kitchen may not be necessary in an area where the average buyer won’t know the difference between that and a £5,000 one

- Don’t forget the boring bits. You will need to repair what you already have, as well as building gorgeous glassy extensions. Old roofs don’t last forever

- You may have to insulate. There is talk of new regulations next year, under which people spending more than £8,000 on their home will have to spend a further 10% of the cost on improving thermal efficiency

- Don’t base your pricing on the lowest common denominator. The cheapest window will not necessarily look right in a period house. Instead of paying £5,000 for windows, you could end up spending £20,000

- Save extras until the end. If you have cash left over, that’s the time to spend it on classy light fittings, floor coverings and bathroom fittings

- A comprehensive specification of works, with detailed costings for each item, will act as a foundation for the project and can save a lot of money. You can then trim things until you get down to a budget that suits your purse

- Inevitably, products won’t be available at the right time, on-site conditions will lead to changes of plans and weather will cause delays. A detailed document means you can’t be held to ransom for extra costs

- Plan ahead. You don’t need to spend £2,000 on the best shower cubicle. A £1,000 cubicle will serve as well, but may have to be ordered in advance. If you decide halfway through a job that you want underfloor heating, it will cost more than if you had planned it from the beginning

- Separate the roles of the architect and project co-ordinator; then everybody can concentrate on what they do best. It will cost 10%-18% of the final contract to have the job managed, but it should save money, time and stress. It also ensures you have certificates showing the work has been done properly. You’ll need these if you sell the house

- Enter into a formal contract with the builder. A Joint Contracts Tribunal building contract will set out procedures to cover disputes, time-frame penalties and proper valuations, as well as ensuring the builder gets paid. Ask your builder for a copy of the contract.

Times recommends

• Second homes: credit crunch casualty or money-spinner?
• How I built my own sliding house
• Top 10 incentives for house buyers