Depending on the style, anime hair can be very complex. However, if you break it down into its basic components, the process of drawing anime hair becomes a little simpler.
Like real hair, anime hair is composed of many strands. However, rather than drawing each individual strand, the hair is often drawn in various sized/shaped clumps, as shown here. These are some of the simplest forms of each hair style. Notice that in most cases, the outline is more curvy on the bottom of the hair clump. This is especially apparent on the top leftmost example; the lower line is curvier than the top line, giving the hair more depth and more of that anime-ish look. Sometimes this is highly exaggerated, and other times it is hardly noticable, but for most anime hair styles, each individual strand of hair will have this basic shape.
Once you know how to draw each strand/clump of hair, you can start putting them together to form more something that more resembles anime hair. The same similar shapes generally persist throughout many different hairstyles. Making one line curve out more than the other on each strand can really help to flesh it out.
Another thing to keep in mind is that you can make the hair as detailed as you like; just keep adding more strands.
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