My youngest daughter had this cute pair of lavender colored jeans that she wouldn't wear because they weren't skinny jeans. This is how they looked...big and baggy, which was not working for her.
She tried them on and I pinned them along the sides where I was going to take them in. You'll notice on jeans that there is a visible seam on the inside of the leg. I choose to use the outside seam because it looks more natural.
Sew along your pin lines and trim the excess fabric. Use a zigzag stitch to finish the edges.
Try them on and make any small adjustments as necessary. (Please ignore her worn out socks in the picture. Oops!)
She tried these on and immediately ran to look in the mirror. She ran back and squealed, " I LOVE THEM! THEY ARE PERFECT NOW!" Oh, to make an 11 year old happy! It's a good day!