Lightroom has so many tools but one of the most handy of these tools is the adjustment brush. Found in the develop module, below the histogram, (refer to image) it allows the user to make precise local adjustments to an image.
With this tool you can either dial in the adjustments yourself or use one of the many presets that come with the brush from temperature preset all the way to teeth whitening. What makes this tool interesting is that it has its own size (you can make it big or small), feather, flow and density controls.
The other handy feature with this tool is the ability to erase parts of the adjustments that you have made. Erase found under the brush menu allows you to remove the adjustment you have made form specific areas of your photo. With the erase button you can make surgical adjustments to your image something that was previously only availabe in photoshop.
The tool does not end there it keep getting better. To make your life easier you have the option of creating two separate brushes A and B. The setting of the two bruishes are indipendent of each other meaning you can dial in specific size, feather, flow and other settings with without affecting the other bruish. You alsodo have the ability to move between the two bruishes as you make your adjustments.
What is our tip with the adjustment bruish? Instead of brushing in your adjustment with bruesh strokes, you can just click where you want you adjustment to start hold the shift key on your keyboard and click where you want your adjustment to end. Lightroom will connect these two points and apply the adjustment accordingly within the two points. This is useful for enhancing things which run in straight lines sun rays are a prime example here.
Talking about sun rays an added tip is to alternate brush A and B. Since light rays usually get wider as they move from the source, you can set brush A to fit the narrower ray emitting from the source and brush B to fit the wider tail end of your ray. You then repeat the step above by first selecting the narrow brush A and clicking on your starting point switch to the wider brush B holding the shift key on your keyboard and then clicking the wider bottom tail end of your sun ray. The result will be an effect that is narrow at the beginning and wider at the end mimicking the form of your sun ray.
The application of this tip is not only limited to sun rays as is with all other tips it is up to your imagination. Enjoy and keep creating.