When you buy dart flights online there is a huge range to choose from. For the vast majority of players a standard shape is preferable due to the fact it is the shape with the most surface area. A larger surface area means more stability in the air and helps to reduce fishtailing or 'wobble'. A smaller shape of of dart flight like a pear, kite or slim for example, will travel faster in the air and reduce the amount of drop between the player and the board, but will be less forgiving for badly thrown darts and can change the angle of attack when the dart hits the board.
A good way to test out different shapes, is to only change the shape of flight on one dart and compare the way it flies to the other two. If you consistently throw better with the new flights then try it on all 3 darts, or better still, head into our darts shop and try out some different set ups.