Hippie skirts are really easy to improv, even for a beginner.
If you're working with a really lightweight fabric, you can just patch together a rectangle as long as you'd like it to be (plus about 1.5" for elastic casing and 1" for hem), and as wide as you'd like the hem to be (60" would be good, I think). Sew it into a tube, sew on an elastic casing and hem.
If you're working with a heavier fabric, or if you want a really wide hem with lots of flowey drape (I've done hems 120" or wider for historical costuming, and they're gorgeous), you'll want to taper it somewhat from waist to hem to keep it from being too bulky around your hips and waist. In that case, decide how wide you want it to be at hem and waist, then plan your panels to taper. For instance, if your hips are 40", you'll probably want your waist measurement to be about 46" (remember it'll be gathered by the elastic. You don't want to be too constricted through the hips.) If you want an 80" hem, you have to taper your skirt from 80" to 46". If you want to make 8 panels, they'll be 10" at the bottom and 5-3/4" at the top - plus seam allowance, 11" at bottom and 6-3/4" at top. Like the simpler skirt above, just sew them together into a tapered tube (like a conic section, remember geometry class?
), sew the hem and make an elastic casing.
