It really is unpredictable but it can be very profitable if you hone your skills to the point in which you can achieve good results most of the time. Analyzing a good altcoin is always the first step to make a succcessful trade.
Trading is all about knowing the analysis and forecasting the market. If you have this art you can easily make the money if market goes up or even if it goes down. Else its a very risky job because you can easily lose out money as you may buy high and prices falls and if it does not rise much you end up making loses for yourself and for client.