I just had what I consider a success with a simple(ish) alteration on a t-shirt, and although I didn’t take a “before” photo and my nightime self-portrait attempts for the “after” shots didn’t turn out well, I still had to share.
A very common fitting problem for me with purchased tops is that if they fit in the torso, they are too large in the shoulders, which can make them look boxy and dowdy. This t-shirt had that problem, so I tried something I remembered seeing once in a sewing book: I used tailor’s chalk to draw a line about 1.5″ in towards my neck from where the top of the sleeve joined the shoulder of the shirt, tapering back to the seamline about 3/4 of the way toward the bottom of the armhole. Then I cut along the line, removed the extra fabric (using a seam ripper to undo the original seam) and sewed the new seam. I forgot to leave myself a seam allowance, but since my seam was just a 1/4″ overlocked seam, it still worked. The shirt will still never be a perfectly-fitting shirt, but it’s better than it was, and it’s comfy enough that it was worth it to me to alter it. I don’t think this alteration would work with woven fabric, though, because the sleeve had to be stretched some to fit back onto the now-larger armhole. The alteration could also make the sleeves too short or make them hang wrong (but I wear these pushed up, anyway).
By the way, for ripping serged seams, or for any seams, really, I find this tool to be far preferable to a traditional seam ripper:
You can find this for a few dollars at fabric stores, or I believe you can find sturdier models (which are actually repurposed surgical tools) at online notions sites such as Clotilde or Nancy’s Notions. I buy the cheap ones and they tend to break where the metal part attaches to the plastic, so I have to replace them pretty often.