1. You Need to Win Their Trust
First and foremost, you don't know everything about your dog's history and probably never will. You can't exactly ask the dog if he or she has ever been mistreated or neglected. It takes time to establish a trusting bond with an animal, and you may need to be cautious in your approach right off the bat. Providing food, praise in a calm voice, and cuddle time will go a long way with most dogs, but it still might take a little time for you to get to know one another -- and that's normal.
2. Introduce Guests and Kids Carefully
Rescue dogs can be very shy at first. They often overcome their timidity with time, but they might be uncomfortable around people they don't know. They also might bark or growl at visitors to your home, which definitely won't make a great first impression. Teach any guests how to approach your dog, and make sure they know the dog's house rules.
Be especially careful around kids, since they are usually small, loud, smelly, and unpredictable. Be mindful of the fact that your dog might not be good around kids and could actually present a danger to them. Even if your dog proves he can behave around children, always supervise their interactions for safety's sake.
If your dog ever displays aggression toward anyone, seek the help of a professional dog trainer immediately.
3. Dog-Proof... Everything
Before you even bring your dog home, you need to exhaustively sweep every corner of your house and re-examine your decor for anything that looks remotely like a dog toy. Used to having shoes strewn about the house or dirty laundry on the floor? Those items smell particularly interesting to dogs, which is why they are such common victims to playful pooches. Either bar access to areas where such smelly things are located, or get in the habit of keeping them off the floor. Make sure your garbage is inaccessible, too, since it might smell particularly interesting to a former stray.
4. Make Sure You Can Afford Any Early Vet Bills
Especially if your dog was a stray, he or she may not be the picture of health when you first find each other. You can expect to have to treat him or her for worms, mange, giardia, kennel cough, and more. Some rescue organizations take care of neutering and getting animals' shots up to date, but some do not. Try to find out ahead of time so you know what to expect. Vet bills are typically not cheap, so make sure you can afford to start getting your dog healthy right from the beginning.
5. Buy a Muzzle for the Vet's Office
Even if your dog seems really mild-mannered, it's wise to prepare for bad behavior at the vet's office. Many rescue dogs are particularly fearful of anyone in white coats and may snarl or snap unexpectedly when approached. Purchasing a muzzle ahead of time is a good idea so you can place it on him or her calmly before you even get to the vet's office. Trying to muzzle a terrified dog is not remotely fun and possibly dangerous.
Adopting a rescue dog can be challenging at times, but if you provide a warm, loving home, your new furry friend will quickly become a part of the family.