One of the quickest and most powerful ways to achieve a signature look in Lightroom is by taking advantage of the HSL sliders. This excellent tutorial will introduce you to the HSL sliders, what they do, and how to use them to create better images.
Coming to you from Chelsea Nicole Photography, this great video talks about the HSL sliders in Lightroom. HSL stands for "hue, saturation, [and] luminance." These sliders provide you a more precise way to adjust global colors within an image. This makes them a great way to change the way greens are rendered for a more filmic look, for example, or make blues pop in the sky of a landscape shot. As the video mentions, take advantage of the targeted adjustment tool; it can be very difficult to adjust areas that are a combination of three or four of the constituent hues by using one slider at a time, whereas using the tool lets you precisely adjust the area with ease. And remember that if you want to make the adjustment locally, you can switch over to Photoshop and use a Hue/Saturation adjustment layer and a mask to apply it only where you'd like.