If the yarn is superwash, you're safe. If it's not, then use lukewarm water so that you don't shock the yarn. Ideally, you use water the same temp as the dyebath you remove the yarn from.
And when setting up the dyebath, make sure to put the yarn in lukewarm water and have the dyebath heat very slowly. I gradually increase the heat dial for the stove eye; then when the dyeing is over, I leave the dye pot on the eye and let the yarn cool completely. Of course with superwash you don't have to be careful. For your first few dye projects, I highly recommend it over fibers that will felt.
- Do you need to use light colored skeins for dying, or will any color work?
The blank yarns are best if you want the dye colors as they come. You can use other color yarn; just remember that whatever color you use to dye will blend with the color of the yarn (like if you overdye pink yarn with blue, you'll get purple)
- Besides kool-aid, what else can you use to dye wool? Does anything dye acrylics?
You can use RIT dye, food coloring, Easter egg dye, acid dyes, coffee, tea...there are all sorts of choices!
Unfortunately, acrylics don't dye. The light shades will absorb a little dye, but not enough to be worth the effort.