There is no right way to knit; there is no wrong way to knit. So if anybody kindly tells you that what you are doing is "wrong," don't take umbrage; they mean well. Smile submissively, and listen, keeping your disagreement on an entirely mental level. They may be right, in this particular case, and even if not, they may drop off pieces of information which will come in very handy if you file them away carefully in your brain for future reference. ~Elizabeth Zimmerman
How many stitches = whatever inches depends on the yarn and needles you use and the tension you knit at. That's gauge and once you figure out the sts/inch for your yarn then you can adjust a pattern. Sometimes you can make a different size - larger or smaller - and come out with something that fits you.