Start small, supply-wise: Knitting equipment can get advanced as you progress. There are many different kinds of needles and an infinity of tempting yarns. You’ll need these for different jobs, but it’s best to acquire them as you need them to avoid going overboard.
Don’t knit off the very tip of the needle: One of the biggest challenges for beginning knitters is that they wind up with stitches that are too tight. To get uniform size stitches, make sure you are knitting on the fat part of the needles rather than at the tapered tips.
Get online: there is a massive wealth of resources online. Knitting techniques, like many manual crafts are easier to show than to explain, so videos are especially helpful if you are getting stuck. Check out the iKnits and expression fiber arts YouTube channels for a start.
Finish your first project: it’s easy to give up or change your mind before you finish your first project. Don’t. Seeing it through will give you a sense of accomplishment, and it’ll be a great memento for when you become an expert knitter. Think of it as a record of your baby steps (or stitches, as it were).
Correct needle grip: there is no single correct way to hold knitting needles. Just pick one that feels comfortable for you.
Take a break: knitting is relaxing, once you get the hang of it. At the beginning though, it can sometimes be frustrating. If you feel yourself getting impatient with a piece of knitting, put it down and come back to it later. This is not an art for the rushed.