I've had great success using clicker/reward training. Started it about a year ago with my adopted/rescue pup who had had very little socializing or training, and was very scared of everything.

One of the trainers I know also says "YESSSS!" if she doesn't have the clicker handy. Her dogs know that it means the same. I've started using it too, with good results with Sascha.

I use the clicker to start training something new, or if we're in an area with lots of distractions. Once the dog knows the command or trick, you can do without the clicker, they just want your approval and/or treat.

Here's another site about it: http://www.clickersolutions.com/articles/index.htm

Good luck!