The red curves in the viewport represent guide hairs that you can style. You can use the tools on the Guide Process tab to style the fur. Typically the first thing you’ll want to do is set the direction of the fur by using the Initialize Guides tool. You can then use the Wind Direction parameter to set the direction of the fur and the Lift slider to create an initial look.
Next you can use the Set Guide Length tool to lengthen or shorten the hairs. Turning on the Randomize checkbox will give the fur more varied length, creating a more natural look.
You can also create bends in the straight fur by using the Bend Guides tool on the Guide Groom shelf. This allows you to determine where the hair will curve using the Curve Mask Ramp (for example just at the tip of the strand) as well as the Angle at which it will bend.
There is checkbox called Limit to bounding box on the Hair Generate object that allows you to focus on a patch of fur instead of having to wait for the entire surface area of the fur to cook as changes are made.
You can the change things like the Thickness and Density until you get the look you want.
If you can’t see the generated hair properly, turn on High Quality Lighting form the Display options toolbar on the right side of the viewport. Also click and make sure Ambient Occlusion is enabled.
You can also dive inside the Hair Generate object and click the Clump Guides tool on the Guide Process tab to add clumping to the fur. You can adjust the Clump Size and Iterations on the Fractal Clumping tab to make the look of the clumping more natural for your model. Turning on Curling will also give your fur a more natural look. By default the Amplitude is set to
0 so you don’t see any changes initially.