Forming Clusters with your Effects Lines are achieved by clicking the Clustering on/off button (A) in the Effects Lines pallete. You can see the Cluster Size Meter (B) in this example is set to 5, which gives 5 effects lines per cluster. The second meter (C) is the Gap Size Meter (set to 3 here) which sets the number of Effect Lines to be omitted between adjacent clusters. The slider (D) is another variance slider and when used gives a random variance in the number of lines used in each cluster.

Applying different strokes can achieve many variations to the rendered effects lines. Here our example Effects Lines have had Eric Jones' excellent Scraperboard stroke applied.

The stroke width was set at "18" in this example ~ of course adjustment of these parameters depends on the type of effect you want to achieve, the scale of the object and so forth.

The above image shows a Variable Width (F7) preset applied to our example Effects Lines. The stroke used here is the "generic pen" - set at a width of "8"

To get fills/gradients in Effects Lines apply a template path to them...otherwise you are just dealing with a set made up of two node lines... and you don't get fills with straight lines...
Alternately, you could apply the template path, select the Effects Lines object and then apply the gradient.

That just about covers most of what I have learned with Effects lines so far...on the next page is an example of an image produced almost completely with effect lines...I hope all of this has helped somewhat! :-)>