I think, and I am no expert... that in the above chart three times the prices went down and held good support at the blue line. You got to see the price charts, binance info has good charts and that bitstamp exchange also has tools to draw on charts.

See 1 day, 4 hr and weekly charts.

Go back to earlier time frames and see the price where there was resistence and support, and try learning it, by studying it, you would get there. Start with the 1 day chart and then study other charts, its fun actually(:

I think you buy at support and expect it to go up till its resistance and sell it off before the resistance point.

You use this with the simple moving average, the macd indicator and even rsi...its more than enough to be a sucessful trader in todays world.