Most knitters choose to knit in one of two styles, Continental or English. If you work in Continental the working yarn is held in the left hand and the right hand uses the right needle to "pick" up the yarn in order to make the next stitch. In English knitting the working yarn is held in the right hand which also "throws" the yarn around the right needle to make the next stitch. I think most people who know crochet first are likely to pick up knitting using the Continental style because how you would hold the yarn most resembles crochet. Also if you hold your hook like you would hold a knife then you're pretty much ready to knit Continental.
I knit using the Continental style (I call it "picking") because it's faster and feels most comfortable to me. I have no problem with the knit stitch, but the motions of my purl stitch were so painfully slow I did everything I could do avoid purling.
One day, I was asked to do a book signing along with a few other childrens book authors. One of the authors was a knitter who wanted to learn how to crochet in the round. So, I taught her to crochet circles and she helped me with my purl stitch. The key is to choke up on the needle. Get your fingers and yarn close to the tip of the needle and you'll be flying in no time. It totally worked. I realized that when I crochet my left index finger holds the yarn away from the fabric because I use the right hook to swirl around the yarn to make the next stitch. But when I purl I needed my left index finger to bring the yarn down over the right needle. Keeping my finger too far from the fabric made it more difficult to bring the yarn down. Today I worked a swatch of stockinette and my purl rows went almost as quickly as my knit rows. I feel liberated.
ETA: It is easier to teach children using the English, or "throwing", method. Their hands are smaller and their dexterity is still developing. So it's easier for them to hold both needles in their left hand while they throw the yarn with the right hand.