Basically, watch the 20 and 80 crossovers. However, the settings of the three stochastics correspond to Fibonacci numbers 55, 89, and 144. Since we have a fast, medium and slow speed stochastics; we can also watch the crossovers. I have found that When the Red (144) is on top, it usually signals a turn upwards; conversely, a blue (89) on top of the others means that the market is going to go down. So red on top = bullish and blue on top= bearish.
You can also think of them in terms of efficiency. If they all display the same and are overlapping in a single line; crossing an 80 or 20 line, this is a strong signal - bullish or bearish. If on the other hand, you see them splayed out and moving away from eachother but the same direction; it signals a more inefficient process and thus a weaker signal.
I really enjoy using these and I hope you will too.
On the settings, I have turned off the %D so that they display only %K's. The Default is 55, 89 ,144.