On youtube try looking up videos posted by Lauratholen. I just took a peek at a couple of hers and they seem pretty good, actually. There was one on making color flow, and one of the videos called "Color flow 2" gives closeups on consistency. I'd watch others, though, to see the final outcome to make sure you'd be happy with the results.
Good luck! Hope this helps! 
The way I was taught years ago was let the color flow drip off a spoon or cake spatula back into the bowl and count one one thousand two one thousand three one thousand. By the time you get the the third count your color flow should be flat and smooth. If it still has ripples and doesn't appear smooth then add a drop or two of water until you achieve the correct consistency. This has worked for me.
Quote by @%username% on %date%
%body%