I already have a wardrobe full of nice dress pants that fit at the waist and hip and are long enough (often my biggest fitting problem with off the rack pants). Most of these pants are that wide leg style, hanging straight down from the hip and about 20 inches around the bottom (or more).
I decided to update the look by narrowing my existing pants. This is easy to do if they have regular side seams (no folded overstitched seams like jeans have).
First you unpick the hem and iron flat. Then try them on INSIDE OUT. Most of the pinning will be done on the outside seam, tapering from the hip, evenly down the leg. I also pinned a small decrease on the inside leg from the knee down. Pin about 1.5 inches from the outside edge near the bottom, and about 1 inch from the inside edge (this will reduce the bottom width by 2.5 or 5 inches in total hem circumference! I like about 8 inches across the bottom (lying flat on the ironing board. Make the new seam really gradually tapered from there to the hipline on the outside and to the knee on the inside.... and make left and right leg the same!!!
Hard to see but the photo shows the larger allowance on the top (pinned) and the smaller on the bottom. These pants have fine lines in the fabric, and I used them for guidelines for pinning.
Finish the seams with zig zag stitch and cut the excess. Re-hem the bottom hem and press really well!