Materials
Wood is the only way to go in my opinion. P.T. (pressure treated) is
great for framing and ok for decking.
The problem with p.t. for decking is that it is always wet, and
that means when it shrinks back all your cuts will have gaps between them.
I have used yellow pine for decking and with a stain it turns out great.
The best way to go about it though is to use 2"x6" or 2"x8" P.T. for framing
and a western red cedar for the deck top or (skin) in 5/4"x 6" boards.
Galvanized hardware and nails are a must for all outdoor projects,
but stainless steel nail are by far the best way to go on a cedar deck.