Just follow the news and rumors. Sometimes like with the current siacoin pump and the litecoin pump from a few weeks ago it's pretty clear what's going to happen. If there's a large consensus that something will pump then it most likely will. If there are any developments around a coin, if some milestone is being completed by the devs, it's price will most likely grow.

With the current bubble it's especially easy to be a trader. A friend of mine I just introduced to the whole thing about a month ago, mined some $10 ZEC with his aging GPU and through trading of altcoins has now made them into $180 without having any idea what he was doing or why these coins pumped. I remember I even had to explain to him how buying and selling works on poloniex. If he could do it anyone can.