There are probably more than two ways to hem jeans, but the two methods I used in hemming the stack here are the simple turn under hem and the reapplication of the original hem.
Here they are side by side.
The jeans on the right were hemmed by just cutting off the excess and turning the raw edge under twice. I chose this method on these jeans because the original hem was worn down and frayed, since it had been walked upon for a few months or maybe years.
The jeans on the left have the original hem sewn back on. It took me more time to do it this way and it was a bit harder on my machine because there were more layers of denim to sew through, but as you can see, it looks tremendously better. You’d have to look hard (or be a seamstress) to notice the jeans were hemmed at all.
The Pretty Poppy has a wonderful pictorial tutorial on how to save the original hem on jeans. The only step I added was to trim the side seam allowances in order to remove the extra bulk rather than trim around the seam and unfold it. I opted for this technique since thankfully the seams on these jeans were not welted. I also ignored her advice to turn the thread tension to the highest setting. It simply wasn’t necessary or advisable. Depending on the weight of the denim, I kept the tension between a 4 and a 7. However, her advice to use the proper needle is spot on. A needle designed to sew through jean fabric is best. There is no way a universal needle would have stood up to the abuse of sewing through at least 5 layers of denim fabric.
I still have 1 pair of jeans left to hem. Despite buying petite, the jeans are about 3 inches too long. Oh, the joys of being short.