When the water in the p-trap has evaporated, sewer gases from below can creep into your house. Filling your floor drains and unused showers or tubs with water is a great way to avoid this from ever happening. Make sure that you take care to fill all drains with a good amount of water. This will ensure that all p-traps are filled.
Keep an eye out for drains that you don’t often use. Not only will the water in the p-traps be more likely to have evaporated, but there’s also a chance that the surrounding area could be dirty. Flushing a large amount of material down a rarely used drain could cause much bigger problems. Make sure that you clean and vacuum the surrounding area of debris. That way when you fill your drains you can be sure that nothing unwanted will go down the drain.