I have fostered many many dogs. Just sign up with any rescue group, they need fosters like crazy in order to save dogs.
At first, you may feel overwhelmed until you and the dog get adjusted. REMEMBER THE DOG NEEDS TO DECOMPRESS..give the dog 2 weeks before he settles in and doesn't drive you crazy with peeing everywhere. It's so worth it at the end. Hard part is when they find a home..but you can always take another one in.