I like the white balance settings in LR - they're simple and an easy way to err..change the colour in your photo.
Some photographers use white balance settings to "correct" a colour cast. Some use white balance to "add or enhance" colour. Irrespective of what you want to do, LR can do it for you with 2 sliders that are there in this section.
I usually use the Temp slider - move towards the right to make the pic a bit more orange or warm. Move towards the left to increase the blue or make it "cool". Which side you move this depends on your colour preferences and at what time of the day you've shot the pic. In most photos shot at sunrise and sunset I've found moving the slider towards the right a better idea than moving it towards the left.
Its easy to go overboard but its not a very good idea so use the slider within limits.
The Tint slider plays with colour a bit more and will add magenta if you move it towards the right and will add green if you move it towards the left however I've noticed it also adds banding to the image if you push the sliders a bit too much.
I usually leave this slider the way it is. Unless its really necessary - in that case I'd suggest you move it by just a few points towards the left or right.
An Example of usage - if its a sunset photo and you like those orange fiery sunsets, you'd move the temperature slider towards the right a little bit so you "warm" up the image a bit more. How much you want to warm up the image depends on what the colour was like when you took the pic. So move the slider a bit towards the right, look at the preview of the photo and accordingly tweak it.
To add some more colour you can then move the tint slider towards the right by about 4 or 5 points. This will make ur sunset / sunrise look a bit more colourful than it was when you shot it.Look at the preview of the image and tweak the sliders till you get something that you like.
One problem here is that when you work on exposure you may have to rework the white balance settings - hence the suggestion of minor tweaks only. You can always come back to this slider after you've moved the exposure slider and then push it a bit more if needed.
In case you dont like the changes you've made you can always select - "as shot" from the drop down menu above the sliders.
If you are using a RAW file you can also select one of the presets from the drop down menu instead of setting WB manually using the sliders. I usually prefer moving the sliders myself as it gives a bit more control of the shade and i like sunsets and sunrises to be nice and colourful.
Irrespective of whether you've got a jpeg file or a RAW file - you'll get an option called "auto" in the drop down menu above the sliders - I dont ever use this option and wouldnt suggest you use it either.
Note - if you are into product photography then ignore what I've mentioned above - you need accurate colour representation and not creative colours. Getting accurate colours is a separate topic by itself. You can adjust WB in LR by using the dropper tool thats on the left of the sliders and then selecting a neutral gray from somewhere in the photo but its outside the scope of this tutorial.
Some purists may be against enhancing colours using WB sliders. I personally see no harm in it. If i can shoot in velvia to make my colours look "better" i dont see why i cant move a few sliders in Lightroom.
Enhancing colours using the Temp slider is something that I've been doing for every single sunset / sunrise that I've shot.
The pic below may look more "natural" compared to the pic above however the colours were enhanced using the temp slider in lightroom -