My first knitting project was a blanket. When a friend told me I wouldn't be able to make a whole blanket on a pair of straight needles (because it would be too much fabric to fit on the needles), I decided to make squares and then sew them together.
I didn't really have a design plan when I started. All I knew was garter stitch, so that was how I did the first four squares. I then learned how to do stockinette stitch, so I did a few squares of that. I got a book for Christmas that taught me seed stitch, moss stitch, and basketweave stitch. By this time I had expanded my color palette and had squares in eight different colors.
I learned how to knit in college, when a friend taught me the basics: loop cast-on, knit stitch, purl stitch, and binding off. For the next several weeks I worked on a practice square. I tried to do a row or two every day. My square was only fifteen stitches across, but during those first weeks one row took me about ten minutes. I realized that I was improving when I saw that my rows were gradually getting tighter, especially on the ends. When my knitting looked smooth enough, I unraveled my practice square and began my first project. I continued to learn more skills by reading books, trying patterns, and watching technique videos online.