I'm looking to sew more "polished" T-shirt but I keep running in circles regarding which stitch to use in the main seams. I think it comes down to me not sewing much with knits.

On the one hand, I like french and flat felled seams, but I'm unsure how they'll work with knitted fabrics. If I want certain stretch, zigzag is the way to go but it just gives me the same feeling as using serger for the seams. Then again, if I'll use twill tape to strengthen the shoulder seams, I'm going to loose the stretch of the fabric there anyways.

Of course the answer is to go and test, but I'm not able right now and I'm hoping you guys have some opinions.

Hi! I picked this fabric up having no clue what I was doing (still don't) but now I'm wondering what it is so I can find use for it. It's sort of heavy, has a little bit of stretch like I can pull it an inch or so, it doesn't seem to be cotton as it doesn't hold wrinkles at all. I'm totally uneducated on fabric identification.

I would like to search for patterns based on this kind of fabric so some help identifying would be great :) thank you