2 mistakes which i learnt from my past trading experience is always use a stop loss even if you are sure enough that a trade would give you profits.
The whole idea ios that if you have not used stop loss and by any chance u are not logged in from of your systemn and the trade goes against you , you might be in a hope that reversal would take place but it could blow your account completely
Second thing is that when you are trading support and resistance , then always make sure whether there is a breakout or not.
because there was an instance, that it was a range trading and i dint realize that breakout happen and i trade in opposite direction without a stop loss by which i blew my account
so learn from your mistakes, either remember or write it down