Did you get that? Some people will try and tell you that you are doing something wrong unless they are a proffesional listen with half an ear, try what they are saying if it makes sense to you but do what feels comfortable to you even if it contradicts what they told you.

The only truly important factor about your throw is consistency. If you throw your darts with exactly the same movements every time you will be more accurate. If you miss just slightly off from where you wanted, you should not move, simply throw the next dart exactly as you threw the last with your aimed changed slightly and you should do fine.

Another important factor is having a smooth throw. Jerking your arm from your elbow or shoulder is a bad practice. Try to throw with a nice, smooth even motion and remember to follow through.

I am not going to preach anything else about how you should throw, you should make your own choices. How you grip the dart, stand at the line, aim your dart, move your arm, use your wrist, etc. will all affect your throw, but they are all very personal.
Just remember the one key: consistency.

How do you get consistant? PRACTICE