How is this simple? I do like subtle hand commands but I start with broad commands and voice. Hand is usually easier for the dog to get at first, then I couple the voice. Over time I can minimize the gesture. My dogs are pretty sure that sitting is a good thing to do 90% of the time, now i can just point my index finger and my dog will sit. The thing about subtle is that you have to be sure that your dog is paying attention to you.
It has to do a lot with the body language which is as complicated as our creation. While we find it difficult sometimes to read our dog, the dogs read our body language including facial expressions rather easily. Average GSD is able to learn over 300 different hand commands before 3 years age. In one of these videos you can see how to make your dog always to expect some hand command, always look into your eyes.