You could always try casting to one of [url=http://www.lewisandclarkflyshop.com/praccasset.html:4df7a]these[/url:4df7a] to help improve your accuracy, although aiming at any object would certainly do.

It just takes practice, practice, practice. Before long you're hitting spots without even thinking about it. Kind of reminds me of when you learn to drive a stick - at first you have to really concentrate on how far out the clutch is and what gear you're in, what does the tach say...but after a while you dont even think about it anymore. You just KNOW.

I like Mozes idea. Marks on your fly line would help.