Pinning pants at the base of the hem

I recommend you pin the hem under, rather than out when shortening pants.  Also I do not believe pinning up at the knee area is a good idea, because pants that are tapered or flared with be different when altered from the base, so you are better off seeing what it will truly look like, rather than thinking it will still be as tapered or flared.

Happy sewing

Judith aka genie