If this is a repost, i'm sorry, but nothing came up on the search.
1. Throwing
This is definitely the easier of the two, and only has one real hint, the rest is just practice.
Firstly, put the throwing item on your bar (therefore hotkeyed), this usually means you won't be able to complete the game on that particular time, but that doesn't really matter, because you can just restart the quest.
1) Stand near the Big Bonfire (sounds like common sense, but i didn't figure it out for a while)
2) Accept the quest
3) Spam the Hotkey with the throwing item, and be ready with your mouse to click on the one with the red arrow.
This will take a few goes to get it right, but it becomes easier as you go along.
Note: The first one changes very quickly, and it is better to let it pass and have a better chance at the second beacon.
[You may find it helpful to zoom out almost as far as possible (this distance can be changed in the interface options Menu -> Interface -> Camera -> Max Camera Distance) so that you have a birds eye view (directly on top) of the beacons]
2) Catching
This is harder, and has more tips.
[You can put the Unlit Torches on your hotbar, but i think it saves minimal time, and does not help you complete the task]
1) Zoom out to a comfortable level, usually just a bit before the total way out, looking directly over your character
2) Light the torch
3) Run forward (it can look deceiving) and USE STRAFE to make sure you get under the torch. You can also use the shadow to identify it.
4) When you catch it the first time, angle yourself so that your throwing it torwards the centre of the area, otherwise it will throw it backwards (as if bouncing off an invisible wall) and make it very hard to turn around and catch.
[note: SW, and possibly other cities do not enable the full amount of zooming out, but i can confirm that Orgrimmar lets you zoom out as far as you like]
If you think it's common sense, fine, but i would've found this useful and it would've saved me some time.
-Kingpin