Don´t forget that the trick to have beautiful brows is not to want the same of some model or picture that you saw.
Eyebrows frame the face and they should be in harmony with you, people with too much space between the eyes should not overpluck in between them and people with little space between the eyes should pluck a bit more.
And don´t forget that most of the people already have a natural brow line, take a good look at your brows and take it from here.
The eyebrows should never be plucked on the upper part that´s why no one should use stencils. And besides, the angle is made taking in care that you make an angle between the side of the nostril and the centre of the pupil of the eye.
As for trimming, it´s tricky but not that tricky. All you have to do is to brush your brows upward and what comes extra besides the natural line you should cut. Then do the same brushing the brow downwards. Don´t cut to straight or you´ll look funny.
Another thing, never wax!
Waxing pulls up the skin and it can make skin flacid. It´s always best to pluck with a good pair of tweezers like the Tweezerman ones.