i use vinegar/baking soda/salt/lemon or orange and a tooth brush to clean the doors, works really well, though it can take 15 or so minutes if it's bad.
also i let the trays soak in same stuff but also lots of water, comes off pretty easy given a few hours to sit.
for inside i don't have any good advice, never had an aweful oven to clean inside, just been using water and a microfibre cloth to get worst out