Contrary to popular belief, socializing a new puppy is not just about having puppy play dates and meeting every person in sight. You need to be mindful and respectful of your puppy’s feelings to protect it from negative experiences and promote positive exposures.
One of the things I’ve discovered is that many people assume socialization is just about getting your dog around lots of people to be fussed and plenty of dogs to play with. This can be part of your socialization package, but remember that the goal of socialization is to get your pup accustomed to and comfortable with the world around it
Breed specific socialisation. Thought should be given to what breed type you have and how breed specific socialisation can prevent a lot of behavioural issues occurring in the future. Every puppy will benefit with the gentle and positive exposure to items and you will find many good puppy socialisation check lists on the internet. In my mind breed specific socialisation is an area often over looked and certain breed types will further benefit from more attention paid to specific areas within the two critical socialisation periods 8-12 weeks and 12-16 weeks of age.
For example, due to the acute ‘sight’ sense of the Border collie, it is far more susceptible to fear the outside environment of busy places with people, loud noises and movement. Therefore more exposure to this as part of your socialisation should be carried out than say another breed type such as a Labrador who will take all of this more in its stride. This is not to say that your Labrador should not have a great positive socialisation but thought such be given of even more exposure in this area to the young Collie.
German shepherd puppies who will develop a strong guarding and protective instinct should undertake a higher degree of people socialisation and people entering the home. A Golden Retriever would benefit greatly from learning to sit on meeting new people from the onset rather than the owner just assuming that the people socialisation checklist has been ticked off with puppy meeting lots of people which have allowed puppy 
to jump up each and every time, which will be a problem to rectify later on. Terrier breeds which a chase and bite instinct should have more of a bias of exposure to moving items, such as brooms and vacuums and learning to remain calm and for these items to be non-eventful to puppy to prevent chasing later on.
Positive, non-overwhelming and confidence building socialisation for every puppy is vital for them to gain confidence in our world but balancing it to weigh heavier on preventing the particular breed specific common issues is often over looked and a really important element of your exposure programme.
Remember: don’t expose your puppy to everything at once, and please do it in a way that is not forceful or overwhelming.