Vic, you should take a look at a book called "Simplicity's Simply the Best Sewing Book" (I think that's the right title). I got mine at JoAnn's, but I think I've seen it at other booksellers. I've been sewing for twenty five years and I still find it useful for sewing tips. They discuss machine anatomy and give guidelines for gauge.
Different fabrics may require different tensions, plus you need to pay attention to stitches per inch and needle size in order to get a smooth seam.
I'm going to sew today! I was going to make knitting needles, but it's rainy. So I'm going to finish a couple projects. Good luck everybody!