I had a pair of the most awful trousers. They were too short and too wide. They were actually given to be by my sister but its so long ago I doubt she remembers now. >.<
I cut the trousers to the desired length. Then ripped out the inner seams of the trousers.
I pinned the material so it started to look like a skirt and then sewed. Usually people cut off the excess material first but I thought I should not cut anything as yet in case of an unexpected mistake. One you cut you cant go back!
I actually had to rip the seams out a couple of times before I got it right.
Once I actually did get it right- which means that it started to look like a skirt and not a pait of trousers with the legs sewn together - I was able to hem the skirt.
I found ironing it in place was far more easier than pinning the fabric in place.
The only thing I had to make sure was that the hem was straight. Not was easy as it might sound.
Then viola! A new skirt! Wooohoo!