Photography is nothing without light. Plain simple and to the point. Once you realize this you will never look at your subjects the same. Just as important to the light is its counterpart, shadows. A combination of light and shadows lends depth and contrast to your images. Controlling and shaping light allows you to change the overall look and feeling of your image.
You will often hear someone say that they only shoot with available or natural light meaning no on or off camera flash. That being said I have off camera flash available to me and as far as I know it is natural, so I use it in conjunction with the light that nature has provided. I will admit it that flash can be hard to understand and at first it is down right intimidating. Another factor that sways one away from shooting with flash is cost, bu there are less expensive alternatives to help get your foot in the door. Full on studio strobes can easily push you up in to the four or five figures. Lets just agree that you are not going to learn how to drive in a Ferrari. I have gone with what is commonly referred to as speed lights, the Yongnuo brand to be specific. As of this post you can find the YN-560IV for $71. The YN-560IV allows you to control multiple flashes and is very easy to use.
The following shot was taken with one speed light fired off camera with both an orange and blue gel. What's a gel, basically it's a colored sheet of plastic that you put in front of your light source to change its color value.
One light is all it took to create this image. The flash was positioned slightly off center of his face set at 1/16th power. The camera was set at 1/200th sec f-10 ISO 320. The smaller aperture allowed me to get rid of the ambient light in the room. Here is the color version of the shot, as you can see the gels gave a bronzing effet to the skin tones which contributed to the black and white version above.
Last but not least a shot including the ambient light and no flash. As a note the above images only had slight post processing done in Lightroom, the big changer in the image was the use of flash.
As you can see I'm not in a fancy studio, just sitting at the the table with my son drinking some cream sodas.
So if you are on the fence when it comes to flash, I say go for it. Practice practice practice, and most importantly Shoot What You Love, Love What You Shoot.