Steam has always been one of the best methods to clean. Make sure you use it where you can.
Spray your microwave oven with soda.a and place a microwave proof bowl with hot water in the middle of the microwave. Turn it on high for 5-10 minutes (it will take longer if your water is cold). The steam generated from the bowl of water will help loosen the muck and make it easy to wipe off.
The same can be done for your oven. Spray it with soda.a and place an oven proof bowl of hot water in the middle of your oven. Turn it on to the convection setting at about 200 degrees celsius and leave for approximately 30 minutes. The fan setting won’t work as well. The steam will help loosen the muck and make it much easier to wipe off. This won’t work for seriously baked on grime (the type that has been there for weeks!), you will still need to get the scourer out for that!