New plugs is always a good start for winter. Usual routine then. Check condition of old plugs for diagnosis. Check for fuel and spark. Perhaps a different starting routine. It's very easy to flood the engine on a cold morning. The fuel air mix condenses in the combustion chamber and on the plug and wets it. At lower temperatures it's difficult to dry this out. Using no choke and no throttle, spin the engine with the button for 2 to 3 seconds. If it fires , catch it with the throttle but it probably won't at this stage. This has the advantage of freeing things up and throwing some oil round the engine. Move the choke about a third of the way and repeat. Still no throttle. If it fires catch it with the throttle. If not. Move the choke half way and repeat. If its not trying or firing up increase the choke in small increments and repeat. Even a new battery won't be giving its best at low temperatures. So the best spark comes as you let go of the start button. This split second as the engine is spinning under its own momentum and the battery is giving its full effort to the spark is when the engine is most likely to start. Therefore it's best to use the button in short bursts rather than hanging on and hoping. If you smell petrol, it's flooded. Go and put the kettle on. The only way to start it quickly is to remove the plugs, clean them and warm them on the gas cooker. Otherwise give it half an hour before you try again. It's a bit of a knack but you soon get used to the personality of the bike once you have some success.