Make a cold frame as a winter DIY project - you can save lots of money, as good cold frames are very expensive to buy.
In dry spells, you can treat timber structures with wood preservative and stain. Make sure you use appropriate products - it is now illegal creosote cannot be used.
Take action to remove algae from paths if they start to become slippery.
Consider installing water collection equipment, water pipes and drainage during winter.
Ensure all stand pipes and irrigation lines are drained to avoid damage from freezing. Put lagging around outdoor taps to enable use throughout the winter.
Add lights and power points to sheds and outhouses, so that you can garden on wet days and in the evenings. Consider wildlife when using lighting in the garden.
When putting lawnmowers and hedge-trimmers away for the winter, ensure that they are clean and dry before storing. Drain out any fuel first, as unleaded petrol doesn't keep, and may cause problems next year when trying to start up the machines.
Clean and sharpen secateurs and loppers ready for pruning of deciduous trees and shrubs over the winter. Special small ceramic tools are available to allow awkwardly shaped and angled blades to be sharpened with ease. Spare springs and replacement blades can also be purchased for more expensive models.
You may want to send garden machinery in for a service while it is not in frequent use.
Garden contractors are often short of work in winter and therefore available to do major tasks such as paving, fence building and pond digging.