grab starts - example
The video below shows Ross Davenport competing in the final of the 200m freestyle at the 2006 Commonwealth Games in Melbourne. Depending on the speed of your connection it may take several minutes to download but should start to play automatically.
The key things to note are the intial pull down, which you can see as the block wobbles, but also that Ross still rocks back onto his heels before his forward motion begins. There is also a slight improvement possible in his streamlining at entry, with one hand on top of the other, but he still gets his body through the surface in a good position.