http://www.teachthought.com/teaching/20-ways-to-improve-your-professional-learning-network/

"Learning networks are based on the theory of connectivism, or learning
from diverse social webs.  Connectivism implies that learning relies on
communicating ideas with others.  PLNs facilitate learning through
meaningful interactions.  The advantages of PLNs today are two-fold.  In
one way, they can improve classroom teaching and help develop new
projects. On the other hand, they act as a form of communal intelligence
that changes societal perceptions."

Twitter is the most commonly used tool among educators for expanding PLN's.  Educators should join an online community for collaboration.  It's important for educators toe active participants and to not be afraid to share.