It doesn't matter if it's a new sewing machine or a used sewing machine from a yard sale. In order to be confident sewing with any sewing machine you have to know how to operate the sewing machine and how to make that machine do what you want to achieve.
I can not stress enough just how important the sewing machine manual is for operating your sewing machine and getting the most out of your sewing machine. If you have a used machine, you can replace the original manual!
If you already have a sewing machine, you may be tempted to just use a bobbin that is already filled from your previous sewing machine. Sorry! Bobbins are not usually interchangable and you can save yourself a bunch of problems by just taking the time to use the correct bobbin for your sewing machine! You may even want to get extra bobbins to have on hand!
Practice on Samples and Scraps
Sewing a simple straight seam using a straight stitch, is the first thing you will want to sew with your sewing machine. Learn to control the machine and your eyes so that you sew a straight seam is not as difficult as you might imagine!
Read through the solutions to the most common sewing machine problems to understand what causes problems and prevent them before they happen when ever it is possible.
Give yourself time to get used to and familiar with everything your new sewing machine offers. Start with simple projects and concentrate on learning to control the speed and settings on your machine.