Diving back into cryptokitties was a huge mistake. Only lost $30 but it was a valuable lesson for me. Never jump onto a sinking ship. I road the wave up, got off for a while, then hopped back on as it headed straight to the ground. Thankfully I cashed out most of my ethereum before hopping back on but still a good lesson to learn.
In cryptocurrency there are lots of highs and lows. When everything is rising you will be temped to hop onto the train but sometimes it's ok to let that train pass because often the train flies back down the mountain after it hits the top. You can catch the next train, or better yet stay on the train that you are already on. Steem and SBD has really surged this month and many of us have profited greatly from that surge, most from stay on the train we've been riding.
If you have done your research, think you can predict the market and have optimism that certain coins are going to increase in value then usually that is a good bet. You've done your due diligence and can make an informed decision. But just because you saw a coin make a big jump one day, does not mean it will do the same the next.
I'm still learning everyday in cryptocurrency and am always on the look out for the next train to catch.