Is it possible to lay a block adjacent to another without looking at the face of the existing block?

I want to build a bridge over a valley to allow fast travelling between 2 areas. The only way I can see to do it is this:

1. Build steps up to the level I need.
2. Move right to the end of the last block placed
3. Turn around so I can see a bit of the face of the last block
4. Place the block so it extends the length of the bridge
5. Repeat from step 2.

This is slow because you you have to carefully navigate yourself to the precarious edge of a block each time.

Is there an easy way to place a block adjacent to an existing block without having to look back from beyond the edge of the existing block?

If my description doesn't make sense I may need to resort to ascii art.

If you sneak SHIFT you don't have to be so careful since you don't fall while sneaking.

If you are putting down that is level just snaek and walk backwards constantly and place your blocks.

A trick to get you stay in sneak mode (on Windows) is to press SHIFT down then press and release ALT release your SHIFT key and click back into the game with your mouse. You should stay in sneak mode untill you press SHIFT again, meaning you can move around without falling off any ledges.

http://www.minecraftwiki.net/wiki/Sneaking

In Windows, you can enable sticky keys by pressing Shift 5 times in a row and clicking Yes. Then press shift twice; it will stay in sneak mode until you push shift again.