Someone asked for a better view of my hand, holding and propelling the shuttle. This clip also gives a little more info on what Peg mentioned, about not curving the weft by pulling the hand toward the body in order to minimize draw in. Again, this clip is from CDWeaver - Weaving Hints and Tips. (To order, go to my website and email me - link is to the right.)
You can see how I hold the shuttle - the tip slides in between the index finger and the middle finger, leaving the thumb free to brake the bobbin rolling off. Then the thumb pinches down on the shuttle freeing the index finger to transfer to the point of the shuttle in readiness to propel it back across the width of the web.
Using this technique I can shoot the shuttle across a 60" wide web.
My favourite shuttle is the Leclerc boat shuttle as pictured. They fit my hand, have good balance, and the spindle stands up completely so that the bobbin can be changed easily with the minimum of hand movements. (Remember my main focus is on issues of efficiency/ergonomics.)
Recently I had an opportunity to weave with a different style of shuttle. It did not have a "flat" backside, but was rounded. I found that the rounded backside caused the shuttle to skew as it travelled across the width of the web (36" as I recall) so that it was very difficult to catch as I normally do because it wasn't the point of the shuttle coming out of the shed, but the rounded backside. So my recommendation would be to keep shuttles with rounded backs for decoration, and choose a shuttle with a flat back to actually weave with if you want to develop a good rhythm.