Maybe you already answered to this question:
first rule is to buy at bottom, or at least when the big fall of price is already happened...as we can buy at bottom and sell at the top...
But how to recognize a coin that is in accumulation phase and then will rise soon or late, without doing a mistake to enter a market that is on his way to die?
looking at this coin,in last 20 days looks like a dead coin without action...i can't see tracks of any accumulation.....but now is going up to 200%
It has a fair bit to do with common sense. It's not all just black and white.
There are several layers to this stuff that you have to be well aware of because it's not just one thing that you can point to and say ah yes that's it, this coin is about to move.
Of course, like you mentioned, there has to be a decline in value (preferably 80% or higher) - which signifies the ending of one price cycle and the beginning of another. But the thing is, with the ending of every price cycle - the next one becomes less and less likely to occur, or takes a little longer to occur... which is why accumulation cycles tend to become more extended over longer periods of time when you are dealing with older, more established coins.
So yes, the decline is an important factor
But, what about when you are attempting to speculate on a brand new coin? Does the decline still matter? Or does sell resistance become a more significant factor? Or is it the popularity of the coin, which occurs as a result of the developers work in promotion, that determines whether or not the price will lift?
You see, there are many things that factor into making your trading decision. It isn't always as simple as noticing a decline, and slight accumulation.
What I will say is, become familiar with using the order book to gauge the sell resistance that lies ahead in the future, instead of using the charts which can only reveal resistance levels as they were in the past. Also become familiar with using the charts to asses recurring patterns, and volume going into/out of a coin.
Once you have done this, you will be able to tackle the many market climates that exist in the altcoin scene