While living in California I worked at a large jail facility. Our uniform shirt was basically a heavy-weight polo. I had three-weeks worth of them and tried my best to take care of them. We had to pay for our replacements and I wanted to look "starched and pressed"...without the starching and pressing. I also wanted a large number of shirts because more often than not I'd need two shirts a shift in order to stay fresh looking. I normally folded them (front down, fold each side in, staighten the sleeve, fold it, and fold once up from the hem. The "Flip Fold" would have been a blessing! They stacked nicely. I had a couple of large drawers to keep them in. I would, sometimes, hang them. I'd hold the shirt by the shoulder seam and fold it in half, the back folded in and the fold line running down the center front of the shirt. Then I would drape the folded shirt over the bar of a hanger. It was "folded" and "hung." Either way presented shirts that were wrinkle free and ready to wear. I always pressed the collars, put a crease in the sleeves, and pressed the embroidered badge and name area, but this took only a minute or so per shirt.

I lay mine flat in pairs and stack them by color in a drawer. I fold DH's in half and place them vertically in a drawer. (He uses them left to right.) I'm curious now about underwear...I fold my panties in half and half again and stack them in a drawer; bras are folded and stacked too. I fold DH's undershirts the way they are folded when you buy them and stack them in a drawer; he uses from the top. I fold his shorts and stack them too. OK, so now...how many of each thing do you have? I remember a survey of men in the UK where the average guy reported having three sets of undershorts: One on, one in the wash, and one clean. I thought that was odd. DH has over a dozen of everything. (They must wash more often, and small loads or by hand. By hand? Ick!)

If you are sewing a stretch fabric with a straight stitch, the stitching will break if the fabric stretches. You should at least be sewing with a wobble stitch (a very narrow zigzag) as it looks straight, but will stretch. To use a double needle, you do need 2 spools. If your machine has 2 holders, put one spool in each. If not then put both spools on a single spindle, but make sure the thread comes off one spool in one direction and off the other spool in the other so they don't tangle. Then thread the machine as if they were one thread until you get to the needle. Thread each needle with one thread making sure they aren't twisted. Use a straight stitch when using the double needle....it will stretch by itself. The other way we always hemmed our tshirts was with the blind hem stitch which is a straight stitch that zig zags left every few stitches. You fold up your hem like normal but then to sew it, fold the hem back under so that about 1/4" of the hem allowance shows and the outside of the garment is folded back. You sew along the 1/4" of the hem allowance and the needle swings left and catches just a pinch of the outside material in the fold to make the blind hem. The video illustrates the technique. Here is a link that might be useful: blind hem stitch

Knits like t-shirts are hard to sew without stablizers. Get yourself some tear away stablizer. It will hold the neckline stable to sew it. It makes it so it won't stretch out of shape. Cut your neckline and iron on a stablizer strip so it's on each side of your stitching line--about an inch strip will do. Take your neck band and sew it together. If you are making it much larger you will have to use new banding material or it won't fit around the opening without stretching it out of shape. If you can't find the right color use a contrasting one. OR-- you can use the existing one like bias tape so it won't matter if it's stretched. Put the seam at center back on the wrong side and pin or baste, then sew on the band. Tear away the stablizer. Turn it to the right side and under 1/4 inch and baste by hand on the right side over the stitching of the side of the band already sewn. Then machine sew it.