When sewing hems on t-shirts and jersey material,  I like to use a double needle.  Thread your machine according to your machines directions for using a double needle.  Press your hem and stitch on the right side of fabric.  Not only does this double run of stitching look nice, it will allow a little bit of stretch to the hem.

When making binding that is a solid color, mark one end of the binding with a marker pen before you cut it into strips.  This can be your right side of fabric or the wrong side, you just need to remember :)  By marking your binding, it will be easier to stitch together and not twist or reverse the pieces.  This is very helpful on large runs of binding.

When you make a quilt, your 1/4" seams are very important.  If you are not using a 1/4" foot as a guide, you can easily check your measurement with your sewing foot by placing a piece of 1/4" graph paper under your pressure foot.  Make sure that the needle comes down in the predrawn line.  You can now easily see where the 1/4" seam allowance lines up with your foot.  You can mark your machine with tape as a guide for the 1/4".  Your blocks will come together so much easier when you are sewing an exact 1/4" seam allowance. 

We all run out of things sometimes when sewing.  If you are sewing jersey and do not have any bias tape for the shoulders.  Cut a thin strip of cutaway stabilizer and sew this into your shoulder.  It will help your new jersey maintain its shoulder shape without over stretching.