6. Tree lights
With the Pen Tool, roughly draw a zig zag path from the top to bottom, and apply the Scatter Brush you've created in the previous step. Notice how the light bulbs are randomly rendered base on the range values you've entered in the Scatter Brush Options, and you can change these setting at any time by double click on the Library object. If you want to have more lights, create another path and apply the same Scatter Brush.
Final
Download the source file now and see how it is done!
Click to enlarge
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