Mistakes to avoid for beginners / Inability to manage orders.
When you place a market order and leave it open, it means you enter a trade at market price without instructions to close the order. In other words, you are playing with the total value of your account. In order not to lose everything, he is urged to set up stop loss at each position opening.
For example, if you are long on the GBP / USD, you can set up a stop loss that will automatically sell your position if the rate drops to a certain level, pre-determined. Thus, you can significantly limit the amount you can lose on a given trade, even if you are unable to sit at your screen all the time.
Similarly, take-profit orders can guarantee a profit by liquidating a position when a predetermined price is reached. So you only need to identify the price at which profits will be taken.