If you are working with a new client, find out as much as you can about their business and what they want to achieve with the design work they have commissioned.
Focus on the objectives of the project as early on as you possibly can, and if the client isn't thinking objectively then encourage them to.
CHOOSING & SPECIFYING PAPER
This is one of the most crucial decisions you can make. You should decide this as early on in the design process as possible, before you start designing the work.
Different paper and board stocks with vary in price by a large margin depending on their finish and quality.
Availability of stock is another area to consider, paper stocks need to be pre ordered from the manufacturer.
If the end design has to be sent to the client by mail, the client would also appreciate if if the weight of the design is kept to a minimum.
The choice of stock isn't just based on the price and availability, you should consider the durability and tactile qualities of paper stock will greatly influence the value and tone of the product.
You should build up a collection of swatch books which can often be given free by the manufacturer - this will improve your knowledge and make your choice easier and faster.
A bad choice of paper choice is an expensive mistake - TALK TO THE PRINTER before and listen to what they say. To a certain extent the choice of paper will point you in the right direction for your design.
EG; paper for use on offset lithography machines should ideally have a low moisture content to help with the drying process.
Gravure is best matched to paper stock with a very smooth surface with no small abrasions, so for a gloss or matte coated stock.