Ice cubes are one of the best ways to cut down the pain of tweezing, and reducing pain is key if you're just getting started with eyebrow grooming. Wrap an ice cube in a paper towel and hold it to the skin under you eyebrow for about 30 seconds. When you begin plucking out stray hairs, some of the sting should be taken away. You can repeat holding the ice cube to your skin as you go along to continue numbing each area.
If you're concerned about ensuring you get the proper shape, consider using an eyebrow pencil to draw the shape you're looking for. Look through magazines to find a shape you like then draw that design around your brow, making a sort of stencil. You can then pluck out any hairs that fall outside this stencil. A white eye pencil, which can be found at most beauty supply stores, works well for this, as the drawing can easily be wiped away when you're done.
Using angles for your tweezing method will ensure you get the right-proportion brow for your eye. Use a makeup brush and hold it vertically against one side of your nose, with the top of it hitting the inner part of one brow. Where the brush hits should be where your eyebrow starts, and you should tweeze stray hairs beyond that point. Then turn the makeup brush so the bottom of the brush is still at the nose and the top of the brush is at the outer corner of the brow. This is where your brow should end, and you can pluck any hairs that fall beyond that point.