If you want to learn how to crochet, just go for it! You will make mistakes, but don't get discouraged. Start with something small like a scarf, so that you can finish it relatively quickly and get some gratification from it. Take a look at my first project. Generally, whatever mistakes you make in your early projects, just go with it. You'll laugh later when you look at it!
What you need to begin: a hook, and a skein of yarn.
I highly recommend Susan Bates brand of hooks. They are sold at every craft store I've found, but they are not available at Walmart. Walmart only sells Boye hooks, and I do not like them. They are harder to work with because the head of the hook extends further then a Susan Bates hook. I discovered this because I used a Boye hook once and was having unaccustomed issues with the hook catching on the fabric. That led me to compare the hooks, and to the discovery of the difference in head height. My personal favorite hook is the J hook. Susan Bates J hooks are yellowish gold in color and cost about $2 before coupons.
A scarf generally takes one skein of yarn to complete. If you want stripes, you'll obviously need a skein of each color, but you won't use them up. There are two brands of yarn that I like for scarves. I Love this Yarn (only found at Hobby Lobby) and Simply Soft (found everywhere) feel good on skin and are easy to work with. Pick a color or colors that you like, and get started!
There are many tutorials online on how to crochet. A good video tutorial is at Art of Crochet by Teresa. She talks you through chains, single crochet, and many other stitches. She goes slowly, talks you through it as she does it, and even has some slow motion. This is very helpful as it can be hard (at least for me) to slow down the motions of crocheting.
Here's a very simple scarf pattern:
Row 1: sc in 2nd chain from hook, sc across (20 sc)
Row 2: ch 1, turn, sc across (20 sc)
Repeat Row 2 until work reaches desired length
Finishing: fasten off, weave in ends.
This means that you will chain 21, then insert the hook into the second chain from the hook and pull up a loop (2 loops on hook) then yarn over and pull through both loops (this is a single crochet stitch). Continue that to the end of the chain. *Chain 1, turn the scarf over so that your hook is on the right side of the fabric, and single crochet across.* Repeat area between the *s until the scarf is as long as you want it. When you are happy with the length, cut the yarn. There will still be a loop on your hook, pull on that loop until the yarn is pulled through. Pull that tightly and then work the ends into the work. This is easier with a yarn needle or a smaller hook (like a size G), but can be done with the size J that you have. Then you are done!
One project and you'll be hooked! That's what happened to me. Happy hooking!