Ok folks. You want to make a beret? Like to knit. Well I have a pattern worked out that is perhaps the simplest pattern on the face of the earth, that's very very flexible. It's so flexible that I don't even need to give you a number to cast on, and you'll still get a good hat in the end. I promise.
Cast On an even number of stitches, the precise number of your choosing, onto your smaller circular needle (I cast on using the large needle and then switch to the smaller, but whatever you prefer.) This needs to fit around your head. 90 is a good default, or starting point but alter depending on your needle size, head size, and yarn size.
Knit in K1 P1 ribbing for 5 rounds.
In the next round K4, M1 around.
Knit 4.5-6 inches in st st.
In the next round, K3 K2tog around. Knit 5 rounds even in st st.
In the next round, K2 K2tog around. Knit 5 rounds even in st st.
In the next round, K1 K2tog around. Knit 2 rounds even in st st.
In the next round, K2tog around. Knit 1 rounds even in st st.
In the next round, k2tog around, and draw yarn through remaining stitches.
Block/Felt/Full the hat as you see fit. For me this generally involves rubbing it vigorously in hot soppy water in the kitchen sink for about fifteen minuets, but I have experience with flat felting so it might take people without that experience a bit longer. I don't generally trust the washing machine for small things like this. Whatever method you use, when it has felted down enough stretch the hat over an appropriately sized dish. Let it dry about half way, then take it off the dish and shape the brim so that the entire hat is round and lays flat. At this point you need to pay attention to the size of the head hole. Don't use a measuring tape, but the dish tends to malform the shape a little and this needs to be corrected. With a steam iron, steam the hat in this shape, and let it dry the rest of the way.
And there you have it. A beret.
Read on for notes about the needle size I generally do the ribbing one or two needle sizes smaller than the main body of the hat. I've had good results using size 3s for the ribbing, and size 5s for the body. I've also had success with size 5s for the ribbing and size 8s for the body.