Here are a pair of jeans I purchased from the Salvation Army Thrift Store located on State St. in Ann Arbor. I got these on Labor Day 2015 during their Half-Tag Holiday sale, so they only cost me $3.
They were in excellent condition, fit great and I doubt they had even been worn; they were simply too long.
First, I determined I needed to shorten them by 3 3/4-inches.
I then divided that measurement by 2...
... placed the seam gauge just above the existing hemline to mark the fold line...
...folded the leg at the chalk line mark...
...and sewed the stitching line just above the existing hem.
I then cut out a section of the side seam where most of the bulk is located so I could fit it under the serger presser foot to cut the excess fabric and overcast the cut edge.
I pressed up the serged edge inside the pant leg...
...so the new hem could lie flat.
This process took all of about an hour, and made being able to wear these jeans so much easier.
I love this technique and will absolutely use it again!