Having got your sewing machine, the first thing to do is learn how to use it. Read the manual, if you do not have one, get one. These days, many manufacturers’ allow you to download copies of manuals from their websites, or at least have a contact point for you to get in touch with, so that you can request one.
The basic items you need to make yourself familiar with are:

• How to change a needle.
• How to wind, insert and thread the bobbin.
• How to thread the machine.
• How to adjust the tension; top and bottom (if available).
• How to select the stitch type and adjust its width and length.
• How to reverse stitch.
• How to raise and lower the presser foot and adjust its pressure.

Threading the machine from spool to bobbin for bobbin winding and from spool to needle for sewing are both critical in achieving a decent seam, so it is important to at least learn the proper thread paths.

You should also familiarise yourself with how and when to service your machine, i.e. how to clean and lubricate it.