Puppet its all about timing. i think most folks get burned by greed though

Timing
When to get in(do your market research, look at everyone's opinion subjectively)
When to hodl(div projections to achieve ROI vs share price ROI or a combination of the both, maths)
How long until it turns sour(guessing game)
When to get out(see greed factor)

The Greed factor
e.g. set yourself a goal return (be fucking realistic) ie 15% roi. When you achieve it dont let greed overturn your decision

rinse and repeat

Disclaimer: I have fucked up on pretty much all of these, but learnt the lesson to not repeat it