When you're first starting out with lighting, the natural thing to do is use your on-camera flash or a hotshoe speedlight. However, unless you're going for a very specific look, this will generally not give you the best results. This great video shows you how even just a single speedlight can give you great results when you move it off camera.
Coming to you from Miguel Quiles over at Adorama TV, this helpful video will show you the results of using an on-axis, on-camera flash, bouncing it, and then moving it off camera. Simply put, one of the quickest ways to advance your use of artificial lighting and the quality of your output is to get the flash off the camera or at least bounce it. You'll often notice wedding photographers bouncing their flash off the ceiling or walls of the venue: this allows them to take a small, harsh source and use the architecture around them to create a larger, softer, and more flattering light source. If you're working in a studio environment and have both the time and control to shape the light as you want, you're in the best possible scenario, as Quiles shows in the video. Check it out above for the full rundown.