Dow Theory. In the chart, need to mark the tops and bottoms. And qualify them as Higher Top(H.T), Higher Bottom(H.B), Lower Top(L.T), Lower Bottom(L.B).
Look for bullish trend which is Higher botom-higher top and bearish trend which is lower top-lower bottom.both should contain with higher volumes.
If Higher Bottom, Higher Top pattern is seen with volume then trend is bullish, so buy right after higher bottom, higher top breakout is seen. If Lower Top, Lower Bottom pattern is seen with volume then trend is bearish, so sell right after lower top, lower bottom breakdown is seen.