One of the most vital elements to a successful foster experience is your partnership with the group that you work with. These are the people who will "ideally" support you during the weeks and months that you have your dog.
You should never feel alone with this big project. Make sure the group you hope to help has a good track record with solid adoptions, and that they take matching foster dogs to foster homes as seriously as they take creating those final adoptions. It is a good idea to look over a group's foster home contract in advance to make sure you like what you see. Will they help you with obedience training? Vet care? Your family vacations? How will they problem solve and promote?
In return for being a good support system for you, your group will want to know that you are willing to follow their guidelines and instructions and that you will be good about communicating questions and concerns that will undoubtedly come up along the way. No question is stupid - really. Ask, ask, ask.
An experienced rescue group will want to get to know you, your lifestyle, and your skill level before giving you a dog to foster. They will want to see if your personal dog has good manners and if he is comfortable with sharing his home. (Your dog does not have to be friends with your foster dog - but he should tolerate its presence.)
They will also want to make sure that everyone in your household is okay with the project and willing to participate in some way, especially, with double-checking those doors and gates and reinforcing the new house manners you will be teaching the dog.
Fostering can be long term, so be ready to make a commitment. It's fun, it is rewarding, but it can take time to find the right match for your foster. Know your own pets and their needs. If your personal dog is 15 years old and wobbly, let the rescue know so they can match up a dog that will be suited to yours.
Just because your dog does not chase cats, does not mean a foster will not initially think that is a fun game. Let the rescue know if you have a cat, make sure your foster has been cat tested, and follow introduction recommendations that are provided.
Fosters might have, or develop, a behavior you find odd or interesting. You may find tail chasing cute, but it can be an obsessive behavior that has to be handled. Always bring up any new or odd behaviors to the attention of the foster coordinator. They could signal health issues or a behavior that needs to be addressed with training.
Let you neighbors know you have a foster, and if possible, have them see/meet him. If he inadvertently gets out, they may recognize him. And most of all love your new friend.
Show your foster what it is like to live with a loving, caring, fun, family so he will be ready for his forever home. Remember you will be sad when it is time for him to leave. But the joy of watching the right family meet him is a tremendous gift you just gave to the rescued foster. Please be not sad, but consider how many more desperate dogs are eagerly waiting for you to give them the once in their lifetime opportunity to share their life and help them find their forever home too!