Introducing a New Dog Into Your Home:     
Before bringing a new dog into your home, it s most important to research the breed and it's inherent characteristics and needs.  This includes, but is not limited to: size, health care, grooming and maintenance, exercise requirements, and particular skills that dog inherently has.  For instance, a working breed needs a job to do, a hunting/sporting breed or a tracker, such as a beagle who is obsessed with keeping the nose to the ground, need to be able to utilize their skills in some way, or they may get very frustrated.  Frustration can lead to anxiety, dominance, and aggression, or simply getting into trouble.
     Also, the age of the dog, and age of any people in the household, are of concern.  An adolescent or older dog may not need as much of the general puppy training and attention, and may have decreased energy levels.  Perhaps that's a better fit for older or less active folks, or for a busy family. 
      Be sure you can provide the dog the exercise and mental stimulation it requires, or they will be bored, and likely to get into trouble. A more intelligent breed, such as the Doberman, Border Collie, Poodle, or Shepherd, will require more mental stimulation.  I always recommend hiring a good trainer to provide you with the proper tools for positive reinforcement training.  Mental stimulation for any dog, is an amazing tool.  It creates a bond between you and your dog, and builds confidence and trust for everyone.  This leads to a dog who is much more likely to listen to you.  A dog without exercise, discipline, training and affection is NOT a happy dog, so don't kid yourself thinking they're happy being out of control.
     It's often thought it's best to get a small dog when you have young children, but this is not actually true.  The small dog can get hurt or abused by young children because they don't know how to be gentle enough.  
     Do yourself a favor, and contact a professional trainer to help you select the right dog for your family.  A good trainer can spot potential temperament/behavioral issues more easily than you are able to.  The last thing anyone wants is to have to return a dog! Then get started with training right away.
     If there is another dog in the household, be sure they are a good match together.  Typically a male and female is best.  Have them meet on neutral ground, away from home.  Walking them together, with you as the leader, sends a strong message, and builds a pack bond.  Set the rules from the start, and you'll be less likely to have to correct problems later.