Now back to the other kind of tension...Its all about how you hold your yarn, which controls how tight your stitches will be. Too loose, you get a sloppy mess. Too tight, you can't put your hook back in it to make another stitch. Personally, my tension tends to vary depending on what kind of yarn or material I'm working with, but its usually on the snug side. This is a tutorial on the proper way to hold the yarn. The crochet gurus out there may be about to gasp and faint when I tell you this, but when my tension is too tight, I drop the yarn off of my fingers, leaving it only on my pinkie and forefinger. That helps me...will it help you? Try it. Since my tension is never too loose, I can only assume that this trick may work the opposite way; Try wrapping it around an extra time in a way which is comfortable and allows the yarn to glide smoothly. Anyone with tension problems, please let me know if this helps you.
To begin, hold the yarn between your pinkie and ring fingers. Wrap the yarn up and over to the outside of your pinkie.
Bring the yarn under your pinkie, over your ring finger, under the middle, and finally over the forefinger.
As I mentioned, I don't hold my yarn the "proper" way. You don't have to either, as long as your yarn isn't getting tangled or mangled, do what is most comfortable for you. Just make sure you're not putting yourself at extra risk for an injury by overextending or cramping your hands.
Its almost impossible to see in this picture, but before you begin, there should be a slight gap between the hook and the yarn, with the yarn on the shaft and not the tapered part of the hook.
Now begin crocheting. It is better to start out too loose when learning, otherwise you'll be fighting to get your hook into a stitch. The hook should glide smoothly in between the yarn, you shouldn't have to force it. Don't get discouraged! Try different ways to hold your yarn if you're still having problems after some practise. I've even seen a tool which fits on your finger as a ring would, and it has a channel for the yarn to run in. Something like that may even help someone with arthritis or disabilities. Try it! Where there is a will, there is a way.