Kitchen, bathroom, utility room:

• keep bins covered or locked, and if that's not possible store them in a cupboard or room that your foster friend can't access
• keep all food out of reach 
• keep bathroom doors closed
• close all spaces in which a small mammal could see as a hideout (behind furniture like the fridge, the gap under the door, anything that looks small and dark and the perfect place for a small animal to make a nest in)
• keep all medication, chemicals, toxic cleaning products safe from your foster friend (it may be best to keep them in a locked cupboard, or in a room they can't access)

Living room:

• place all poisonous plants out of reach of your foster pet
• pick up anything that could be dangerous
• put away everything that is of value to you and your family members. Lots of animals explore the world with their mouths, and for some, even every day things like charging cables look like tempting, but deadly, treats. If certain things can't be removed, consider installing bite proof covers.

Garden:

• make sure that your foster dog cannot escape from your garden and that the fencing is sufficiently high if they are inclined to jump up.
• If you're fostering a cat, it is advised that you do not let them outside to prevent them from running away and getting lost.

Garage/shed:

• look at what you keep in your garage/shed and make sure that all dangerous products are kept locked away or at least out of reach for dogs and cats. Best practice would be to ensure garages and sheds remain closed and locked when not in use.
• If you do need to go in, before you leave make sure you haven't been followed to ensure you don't accidentally lock your foster friend in!