When it comes to the shape of your brows, here is the general rule for shape. Start by placing a make-up brush or pencil along the side of your nose, this is where your eyebrow should start. Then turn it slightly so the brush/pencil is still resting on the edge of your nostril but is now running along the outside edge of the eye, this is where your eyebrow should end. Finally, if you keep the brush/pencil at the edge of the nostril but this time run it through the iris of the eye, this is where the point of the arch of your eyebrow should be.
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Once you have your eyebrows in the right shape, you should use make-up to define the brows. Now be aware I am not suggesting you have to colour your brows in like a clown, but just that with a light hand you can define the shape and colour of your brows to make them look perfect.
There are many different products that you can use for your brows, for example, pencils, powders and gels that can all be used to create the desired effect. Whichever medium you choose, use light feathery strokes this will keep your brows looking natural.