You can use any color disc, but I find white to be the best, because the glow will reflect somewhat off of the white color and make the whole thing easier to see.
I put 3 strips of packing tape down across the whole width of the disc, so the taped area ends up being about 5 inches x the width of the disc. It doesn't need to be this wide, but I prefer that to not having enough tape and having the slippery glow crap leak out onto my disc.
A 3 x 3 paper towel square is more than enough for one side, and it doesn't require too much glow. I just cut a glow stick and squeeze drops onto it. Usually 7 or 8 drops is more than enough -- enough to get the square somewhat covered without soaking through it. Too much glow can often leak out of the sides of the tape (and when you throw sometimes it'll splatter and look like Predator blood). It will stay lit for 4 to 5 hours easy, and I haven't noticed much change in flight. Sometimes, if I have too much tape on, it affects the grip of my thumb.
The tape I put over the square is just enough to cover it and make a good seal. I put the tape over, and press down on the edges of the tape, but I don't press down on the area where the paper towel is. Then the glow acts like a toothpaste tube and shoots it out one side or at least spreads it.
Much of it is trial and error -- finding out how much tape you really need, how much glow is sufficient, etc. I don't play glow often, but I've had no problems with this other than it sometimes being too bright. You want it to be bright enough to see from far away, but not so bright that it ruins your night vision when you're trying to line up a putt (and believe me, it's easy to do this). That's why I use a Super Glow Wizard for putting, because it's a very soft glow. Not easy to see, but doesn't affect my eyes when putting.
"a man is a success if he gets up in the morning and he gets to bed at night, and in between he does what he wants to do."
-- bob dylan