Vector art needn't be simplistic if you're willing to combine Illustrator's functions in innovative ways. In this tutorial I will demonstrate how to use symbols and clipping masks to bring interesting textures into your illustration work.
When you store artwork as a symbol, you can add it to the artboard as an instance as many times as you like. One advantage of using instances is that they're more memory efficient. The processor only has to process the data once, because all instances refer back to the original in the Symbols palette, making functions such as printing or raster image processing when going to press faster and more efficient.
There's also a workflow advantage because an instance on the artboard is immune to core editing, which prevents accidents when your files get complicated. You can perform basic edits to an instance by re-sizing or rotating the bounding box contents, or by altering Transparency and Blending Modes of the instance as a whole, but you can't access individual components or alter Fill or Stroke attributes.
Once you've created numerous instances across an area, you can group them and trim with an object. Converting this object to a clipping mask ensures that the group below is only visible within the mask area. This is an excellent way to constrain your patterns to finite areas. And you can still edit a group or clipping mask at any point. Double-click the group on the artboard to edit individual components, or reshape your clipping mask with the Direct selection tool. Building up your artwork in this way ensures every component remains editable, so you can create beautiful images.