US size 8 (5 mm) needles and category 4 (medium - worsted weight) tightly twisted, smooth yarn in a light color.
I teach knitting to people ages 6 and up in a drop in clinic. I have taught for more than 25 years in a variety of venues from formal classes to youth groups. I have seen people struggle with needles or yarn the wrong size and determined this is the best combination for beginners. It is large enough to see clearly what you are doing, and small enough not to be awkward.
Some people will recommend larger needles and thicker yarn because it is even easier to see, but what I have seen universally is that this causes the stitches to be too tight. Why? Because the beginner doesn't consistently get the stitch to move past the point and onto the barrel of the needle because the distance from tip to barrel is too long. That means the new stitch never reaches the full size it should be and is difficult to push on to the barrel when other stitches are added and the point becomes full.
Choose a light color because darker colors are harder to see.
Choose a smooth yarn because hairy or textured novelty yarns make it more difficult to make out the stitches.
Choose a tightly spun yarn because loosely spun yarns allow the needle tip to penetrate between the plies which messes up your stitches. A tightly spun yarn will guide your needle tip into the loop instead of through the yarn itself.
This is my favorite beginning knitting video: http://www.youtube.com/watch?v=3uw-nUvGrBY
It covers the cast on, knitting, including starting the second row, and binding off. The cast-on she demonstrates is a good all-purpose cast on that will work in more than 90% of projects. Unlike the backwards loop cast on, it is easy to knit the first row.
For additional instruction, check the following resources:
http://www.knittinghelp.com/videos/learn-to-knit
http://learntoknit.lionbrand.com/
http://www.purlbee.com/ (scroll down the right sidebar to "knitting tutorials"