What do you look for at the neckline and right shoulder to predict its next move after completing a head & shoulders formation?
Using an Elliott Wave interpretation, the "right half" of the entire H&S top is expected to trace out a 3-wave pattern. The right-side of the head is the a-wave. The left-half of the right-head is the b-wave. The right-half of the right-head is the c-wave. As a rough guideline, the a & c waves should have ~same magnitude. The b-wave ideally will make a 50% - to - 62% retracement of the a-wave. You want to be positioned ahead of the breach of the neckline with the c-wave if you're able to identify the H&S formation soon enough.
Sometimes the graph price value decreases below a long term trend line. I might look for divergence between the price curve and the RSI or MACD curves.