I don't know that there is a "proper" way per se. Probably as many ways as there are ringers. However, down and dirty way is to simply hang the hook from your index finger and thump the barrels with your fingernail. When available I prefer to use a small piece of metal. Doesn't take much of a thump. as mentioned somewhere above sometimes the extractor/ejector needs removing to get the barrels to ring. Just don't make a big project out of a simple test.

John McCain is my war hero.