Roving from http://juliespins.etsy.com

The singles

Plying

Finished!


WET SPINNING
Wet spinning isn't really "wet". I think a more accurate name would be "misted" or "slightly damp".
This technique is very helpful in achieving a smoother, softer yarn. The moisture on your fingers will enable you to gently manipulate the ends of the fibers into the twist.
To do this, slightly dampen your fingers on the hand that is controlling the twist, either with a spray bottle/plant mister, or a few drops of water from a bowl or cup. Once you get to spinning, you will see how once the fibers touch the dampness, a bit of spinning magic occurs. Some spinners use natural oils such as lanolin as their lubricant. It's all a matter of personal tastes and finding what works best for you.
SETTING THE TWIST IN PLANT FIBERS
Setting the twist on a plant fiber uses a different method than with wool.
You will need to give it a quick (a minute or three) bath in some boiling water. (Some plant fibers, especially certain cottons will take longer.) In this case, add a few glugs of vinegar, on occasion the recycled silk sari likes to bleed dye, and the vinegar helps to ‘set’ it. Use some tongs or a large wooden spoon to remove your yarn from the boiling water. Once it has cooled enough to touch, give it a few good whacks & hang to dry. It is perfectly okay to block or weight down plant fibers when they are drying, it won't have any ill effects on your knitting yarn. Have no fear if it feels a bit rough. Both fibers soften considerably with wear and washing.
FLAX
Flax should be spin with little twist and light tension. Wet the fiber with your fingers as you spin, if you want to spin a smooth yarn. Do not use water if you want a hairy textured yarn.
Plying, from Sarah:
Sarah uses the cap from a spice bottle to keep her ply balanced. She starts plying by threading the end of one strand of yarn through one of the holes in the cap, so that each singles gets its own hole. Then she plies normally, and the cap keeps the tension on the strands even so that no little boucle sections form.
People are usually taught (and books usually say) to spin singles Z (clockwise) and ply S (counter-clockwise).
However, you can and might want to consider the end-use for your yarn and the technique you’re going to use to get there … crochet prefers the final twist direction to be Z, since it adds Z twist to a yarn (so if you were to take a final S twist yarn and crochet it, you’d be taking twist out … and if it were singles, this could be a mess if the yarn then drafted apart again …). Knitting depends: British/throw-style knitting adds Z twist and German/Continental/pick-style knitting adds S twist.
I take the leftover on my bobbin and wind it into a tiny center-pull ball. Then I ply it from both ends and make a swatch. That way, I know how the finished yarn will knit up.