First things first, I have to wind the warps before I can dye them. The way that I do my dyeing came about from one of those "I wonder what would happen if I did this" moments. I experimented with different ways of winding the warps and found that to get the results that I wanted, I needed to wind the warps on the warping board. Using a warping reel, while faster to wind, tended to not give me the results that I wanted, the colors would be spread out and choppy in appearance instead of the more organic and flowing look that tends to happen when I use the warping board. So I now wind all warps on my warping board and I do them 1 thread at a time. I find using a paddle on the warping board uncomfortable and doesn't totally keep threads from twisting. Since I really dislike putting on a warp with any twisted threads, I find it worth the extra time that it takes to wind the warp this way. And since each thread goes thru my hand I will generally find all knots.
I now wind the warps in various ends and lengths. The number of ends are either 50, 100, 200, 300, or 400 generally. In a thicker yarn like a 3/2 the maximum number of ends that I can wind is 300. For a finer yarn I might wind more ends. Most of what I use is 8/2 or comparable in size. For length I mainly wind between 4 to 8 yards. I measure the warps again after dyeing and round down to the nearest eighth of a yard to account for any shrinking from the dyeing process. I originally dyed each warp individually but have recently started dyeing several warps together at a time, generally of several different numbers of ends. They can be used individually or combined, the colors will be the same but the placement and possibly amounts of each color will be different.