I was so nervous that when bitcoin price dropped to 6000$ I was scared to loose more and withdrew my coins only to regret later that it became 8000$.
Please help me with your advice /opinion.
Controlling your emotions is the key and do not panic Bitcoins value is getting stronger and it is the most promising coin even if the price falls down it would recover eventually so you should be used to it on the movement of market. If you think you have already gained you can sell it right but it is best if you set a target percentage or goal on when you will sell your bitcoin so that you will not be disappointed.
That is one thing that can never be done for someone who does not have adequate knowledge of their investment. It is actually a very easy thing to say to people to not panic but as long as they are not aware of some of the things that can happen anytime which also includes the risk, it would be like you were trying to deceive them one those times come unless you sound convincing enough. My point is, selling is not the issue, but selling for the wrong reasons is the main thing anyone should not fall for as a result of emotion or panic.
When price cross the previous record sell then otherwise holding more in that time will lead you to the more wait and I have been through that many time because greed is not good when your aim struck simply cash out no need to wait for the more profit because people sell their coin faster and this create and see the price daily to make a mind set to sell at the particular time this will help you in trading to earn good.