Do you always missed the right time to sell or buy bitcoin?
Back in some days,i was trading on forex with regular currencies,and on the start,when i was learning i usually did miss the good price's.
I did actually the same with trading bitcoin when i was starting,and it was happening usually but when i got some knowledge,i had no problems with it.
Hello I am newbie and I would like to know how to deal with trading bitcoin and altcoin

Trading is not an easy job every body will fail to sell at right time because some times it is very difficult to assume what will happen to market. Every altcoin completely depend on bitcoin once bitcoin rises every other altcoin will loose it capability. So every body will fail to sell at right time.
no doubt about this that trading is not an easy job it really need more knowledge, experience and good trading skill including your luck, if you want to become a successful trader you need to get good experience in trading first and only then you can become a good trader.
Experience can be get if you do trading for a longer time, you have to learn from your experience of course to mature in trading, it's not easily but that's the reality when you want to make money, no easy way to do it, it involves your knowledge and your skills to be able to succeed.
Put in mind that if other people can succeed in trading then we do also have a chance, we just have to follow what they are doing and focus on it.