Let us begin with the basics. Your scissors should be silver. This is a very important requirement because a silver pair of scissors is visible very sharply despite your hair color. So you can opt for practically any hair color and the silver scissor will always be clearly visible. This is the reason why barbers and hair dressers tend to opt for silver scissor!
Another basic tip is to use this tip in a slant angle. The angular position helps get a better style and more sharp cut but is also much more convenient to get the shape you want when the scissors are slant. If you are trimming you hair you will realize that this angle is perfect for the right snip.