When to sell?

I've made 2 big mistakes recently by exiting too early. One is China Petrotech and another one is Jurtech.

For China Petrotech, I've entered at 0.39, but sold at 0.42. After selling, it start move up strong on the following days. 7 days later, it hit high at 0.595. I could have made another 3k if I were to just follow the chart.

For Jurtech, I've entered at 0.76 but sold at 0.8. After selling, it continue to move up and today it closed at 0.92. Missed another 3k+.

I have a good reason to enter for both counters and entry point were low, but my exit point were really bad. I'm suppose to sell by following the chart but I've failed and it cost me a total of 6k+. Lesson learnt.....when enter at a good point, just hold until the chart shows sign of weakness on the counter. Will wait for the next opportunity......hopefully MemoryD is the next one to move up, as buyers are start coming in for this counter.