The biggest thing to consider before adopting a puppy is whether you have the time, energy and patience to provide adequate training and exercise. It is also important to consider whether you can afford routine veterinary care, such as spaying or neutering and vaccinations.
Young puppies typically require a large time investment. They need to be taken outside every two hours when they are very young, and fed several times a day. Young puppies may not be able to sleep through the night, and they may cry or whine out of loneliness and frustration. They need to be carefully supervised at all times until they are housetrained and learn what they are allowed to chew on. Puppies may also nip or bite in play until they learn otherwise, which may make them unsuitable for homes with young children.
When choosing your puppy, you also need to consider its needs as an adult. If you tend to lead a sedentary lifestyle or work long hours, you may not want to get a high-energy breed such as a border collie. If money is a factor, breeds known for health issues or with significant grooming needs may not be a good choice.
If you decide a puppy is not a good match, consider adopting an older dog. They are often easier to train and care for, and many of the veterinary and training costs associated with puppies are unnecessary in adult dogs.