Here's my recommendations.
Material: Bamboo (because it doesn't drop stitches as much as metal)
Size: US 8-10 (Meaning any size within that range I learned on a size US 8)
Length: 9 inch straights (added this because I bought some 13 inch metal ones in the beginning and those are ANNOYING. The 13 inch ones were way too long and got in the way a lot.)
Material: Acrylic or Wool Blends (or just choose something cheap, you 'are' learning after all. Mistakes will be a given.)
Texture: Smooth (as everyone mentioned, it's easier to see your stitches with a smooth yarn.)
Color: Light (again as previously mentioned, easier to see stitches.)
When I learned to knit (about 3 years ago) it was on size US 8 bamboo straight knitting needles, using pale yellow acrylic yarn. The person that taught me taught me the long-tail cast on and made me cast on over and over again, for half an hour (thanks to that I never had a problem with the long-tail cast on).
After that I was taught the Knit stitch and got comfortable with that before she taught me to bind-off. After that it was time to learn the Purl stitch. So cast on a new swatch, Knit a row, taught to Purl a row, and continued with the swatch. Your swatches will probably be uneven, have dropped stitches, and have many mistakes, but don't worry and just keep going.
Once you get the basics down you can worry about tension and other things. Side note, I still have those swatches from my lessons.