Clean your oven regularly when cool. Some models have cleaning cycles that burn off dirt.
Wipe glass and ceramic electric hobs clean after each use. Manufacturers supply tools and products for burnt on stains, to avoid scratches.
Clean gas hob grates, drip pans, and burner caps with warm soapy water .
Cleaning the grease filters in your cookers heads every two months allows better air flow. Most aluminium grease filters are dishwasher safe.
Cleaning grease build-up around the fan will help even distribution of heat and increase efficiency.