Wow! That is such a wide subject - so many ways to do it.
In this example, they were all made using the same method.
Make a circle, say 20 points. Copy/paste and scale the copy up - in the case of the skirts, the copy was moved below the original Change the pattern of the points on the the second circle to represent the shape you want. Use Surfaces->Ruled surfaces to join the two circles.
if you need more specifics, just shout
I’m sure there will be others along to show different methods.
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