One of the reasons that I started sewing more of my own garments was because I had to alter a lot of what I bought at a store... My legs and arm are shorter than the average, and my shoulder is a little narrower. So, sometimes I had to basically re-sew what I purchased.
Just recently I was asked to alter a man's vest. It was not a difficult or complicated alteration, but it involves some steps which I'm going to explain below.
The first step is to have the vest on the person and to mark where the new seams need to be for a better fit.
Then, the next step is the tedious seam ripping. Because I have to be very careful not to damage the fabric itself, I am very careful when I rip the seams. In fact, it takes quite a long time.
The third step is to pin the fabric together and mark where the new seams should be. I used a pink chalk pencil to mark where I need to sew below.
The fourth step is actually sewing the seams. The photo below shows the new seam that has been sewn. The actual sewing is very fast because I use a sewing machine. The steps to prepare for sewing is usually a longer process.
Since this vest had a lining, I had to open up the bottom of the lining in the back to get access to the seams. So, the last step is to sew up the seams I opened for access. Again, I had to pin the fabric so that the fabrics don't shift around when I sew. (The lining fabric is quite slippery.)
I think the time it took for me to finish altering the side seams would be enough to actually sew a new vest (provided that I had the fabrics already cut and ready to go, and I am not including the time for making button holes and sewing on the buttons by hand). This is one of the reasons I like to just make a garment myself that actually fit me to my preference.
In addition, store-bought clothes are often not well sewn... (Just imagine people who are under a lot of pressure to sew as much as possible in a factory setting.) This means that if I sewed a piece of garment myself, I can make sure it is sewn with care. Once I have sewing patterns I know that work well for me, I can keep on making the same pieces of garment with variety of different fabrics without worrying about the fit.
Please don't get me wrong. I am all for altering a piece of clothing so that you will get to wear it in confidence. It is so much better than not wearing it after already buying it. If you have something that needs a better fit, feel free to contact me. Or, if you feel like having some custom-made clothing, I am sure I can help, too. (Please see this page for more information on custom sewing and alteration.)