If you want to support everyone by including all the new devices, you need to responsive and choose an appropriate set of information to display.
But if you are supporting the widest range of possible devices capable of browsing the internet then you must support the browsers as well.
Give people a reason to upgrade is always the excuse. But that is not life. Some people have older browsers and that is just life.
Printable Sheets for Sketching Website Designs
There are several great printable templates available for planning your website design. Here are the ones I found most useful.
Sneekpeekit - Printable Sketch Sheets
I recommend learning about the Visual Vocabulary from Jesse James Garrett. The website has detailed information on how to describe information architecture and interaction design. (The book is also a good read.)
Zurb has a set of responsive sketch sheets and a good article on how to use them when planning your responsive design.
Inspiration Hut also has a set of printable papers.
960grid has several printable sketch sheets; their sheets have 12 or 16 columns in them. We use a 12 column grid so I found these sheets most helpful.
If you prefer not to draw your plans by hand, Balsamiq has a program for making wireframe mockups.
Another set of sketch sheets good for showing the movement of parts in a fluid/fixed layout.