if the coin you buy suddenly goes down, what do you do?
panic sell or hold ??
Panic sale is the worst, just give it some time, if it is going only down try to trade it cause maybe other coin will be able to give you some earnings.
If its a good coin then better to hold on it, but if not learn to cut losses because you can still earn it in a better coin. But it will still depend on your trading strategy, always depend on it because this is how we make money in trading. Don't sell on panic always use your skill to prevent big losses.