This is a group of people who make amazing armor and other props for cosplays and they have tutorial videos explaining how they made different armor sets and props.

This is the most reliable site I have found for the affordable types of thermoplastics (heat activated plastic).

This is a smaller but very friendly anime convention that is closer to home for most. It is a great place for first time con goers to start out so they don't feel overwhelmed

This is 1 of the better known and well ran anime convention on the East coast.