If you were going to go run a marathon, you would probably do some warm up exercises before hand, right? Well the same thing is true for your voice. If you want to know how to sing without straining your voice, you need to know how to warm up your voice properly. One of the simplest exercises is yawning. Yep, just yawning. This will get your blood pumping, and help open up the airways in your throat. After that you can do some simple scales. Eventually you can move your scales up until they are hitting the top of your range.