If you’d like to try and maintain the cleanliness of your oven between professional cleans or prevent your oven smoking, try and wipe away spills as and when they happen or as soon as you can. Obviously, wait for the oven to cool before you do this to avoid burns.
When cooking something that might spit or spill, cover it if you can and put another empty tray on the shelf underneath to catch any spills. This will be much easier to clean and helps prevent food from being baked on and building up on the bottom of your oven.