Sewing machine needles will need to be changed often. You may get about 8 hours of sewing out of each needle. Needles will also break and bend so they may need to be changed sooner than that. If you are not sure how to change the sewing machine needle in your machine, please check out a tutorial that I posted HERE on how to change the needle.
What type of sewing machine needles should you buy? There are two types of needles that I encourage beginner students to purchase and have on hand in case one breaks/bends. When you purchase a sewing machine, you will get a couple of extras but these are easy to pick up on sale when the local sewing store has their sewing notions on sale for half off. This is one supply you don't want to be caught without because it will halt your sewing to a dead stop.
Schmetz is a very good brand of needles and can be purchase at almost any sewing store. Universal needles can be used on woven fabrics and some knits (more on that later). If you look at the bottom of the package, you will see numbers like "80/12" and "90/14". Those are the sizes for the needles. For medium weight fabrics like quilting cottons, you will need to use a size 80/12 needle (that is the size that is normally in each of my machines for normal use). If you want to sew on denim or heavier duck fabric or home decor fabric, I would change the needle to a 90/14. The higher the size numbers, the thicker the fabric and vice versa. I have size 8 needles for a handkerchief weight fabric that I have.
Ball Point/Jersey Needles
For sewing with knit fabrics, I prefer to switch over to a ball point/jersey needle. The univeral needle packages say that you can use them on some knits but I just prefer to switch to the ball point. The size recommendations are the same....I use the 80/12 on most all of the knits that I sew. I think I own some 90/14's but I couldn't tell you the last time that I used them because I normally don't sew on heavy, stretchy fabrics.
Hopefully this little primer on sewing machine needles helps you to know what type of needles to buy the next time you are at the store!