So it is now the matter of precaution of someone
As it stands, cryptocurrencies are a huge gamble.
Long-term holding can be good but you need to trust the fundamentals that you determined for each of the coins and hold only the ones you anticipate having a strong future. Mind you, when I say long-term, it's not like a few weeks or a few months. I'm talking 6+ months. And though it's tempting to swing as the markets go, if you've determined to go long on a coin, then stay long. Basically, don't react to the news on those coins and be prepared to stomach missing out on those pump and dumps. There have been many a time this has worked out well for me (the tricky thing is knowing which coins to go long on).
I usually don't talk about my performance in crypto, but as an example, I held about 10k PPC in the sub 0.001 days. This was back in March-April 2013. Then I brought these back to the markets in November 2013 where I sold about half at the 0.006-0.007 range. That was a pretty good long-term hold. I based my holding on the community, the fundamentals of the coin, and several other trading dynamics. But it's an example that if you stick with a coin you feel will perform strongly as a long hold and react accordingly, it can be highly beneficial.
Then you have some coins that work out well for medium-term that you should to follow on maybe a weekly basis and sell when appropriate. Once again, the trickiest thing is not reacting to the short-term trend (i.e. daily/hourly), and to focus on weekly (maybe semi-weekly) performance. And finally you have short-term coins that are best followed on a daily basis. For these coins you may have to focus on the pump and dump aspects where you try to anticipate the markets as movement happens. Personally, I try to stay away from the coins that have only short-term potential.
But it's all dependent on what works best for you and what you're comfortable with.