Tensioning yarn in crochet?

It does take practice, but there are a few things you can do. I put one of those things you put on pencils to cushion them for kids on to my hook, this helps me to relax my right hand, which improves my consistancy. I also don't get that writer's bump on my finger. I hold my yarn and my work in my left hand, that means the hook doesn't have so far to go, that helps keep the tension even. Some people find that if you work on a big project, like a blanket, while you are working on smaller projects, and you do a few rows on the big project to warm up, the tension on your smaller projects will be more even. If you find that you start your crochet tighter and loosen up as you go, that is a good way to keep your projects consistent. I cheated yesterday with a hat I was making, and went down a needle size when my crochet got too loose, it worked pretty well. And yes practice does help.