Summarize this article:

There are a wide variety of beret patterns available at your local yarn shop. Pick one that has an interesting design but that also matches your knitting skill level. Choose a yarn that matches the requirements of the pattern you chose. Usually, a pattern will specify the weight of the yarn to use, so that the beret you make will end up the right size.  The pattern will also specify the size needles you should use. The size of the needle you use will also have a big impact on whether or not you finished project matches the size the pattern was supposed to make. In many cases you will also want to use circular knitting needles for knitting a beret, as the length of the swatch you are knitting is relatively long. Pick out a yarn that will feel nice in contact with your skin. For instance, while heavy wool yarn will keep your head nice and warm, it may be itching where in contact with your forehead. Balance your need for warmth and an attractive look with a yarn that will be comfortable to wear. You may need to refresh your knitting skills a bit before beginning. If this is the case, consider knitting a sample swatch that practices your skills before starting your actual project. This way you can get used to the yarn and the stitches you will need to use in the project.  The basic design of most berets requires that you begin by knitting a number of stitches onto your needles that will equal the circumference of your head. That's usually going to be about 60 stitches to start.  Once you have knitted a few rows of that same length, which will eventually become the band of the beret, you will begin to increase your stitches at regular intervals, making the length of your knitted piece longer and longer. Once you get to the midpoint of your beret, where the flat flare is at its widest, you will begin to reduce your stitches. This will create that signature flat look of the beret. Finishing the beret requires you to reduce your stitches until you are down to around a dozen. Then you will tie all the stitches together at the top. To create the finished shape of the beret you will then work your way down the side of the beret, sewing the two ends of the swatch you have made together. This will form your work into its final round shape. Your knitted beret is finished and it will keep your head nice and toasty warm.

Summary:
Purchase a pattern. Purchase yarn and needles, if you don't already have them. Knit your beret. Make sure the beret fits you and then wear it out!