In case of bullish Marubozu,the open price is the lowest price and close price is the highest price of that underlying stock for that session.
This means that, there were many market participants ready to buy the underlying stock at any price during the session and due to this high demand the price kept on increasing and closed at the highest point for that session. The expectations is that same bullish sentiment will continue for few more sessions and further buying will happen.
Decision: In case of bullish Marubozu,traders should start looking for buying opportunities, buy price should be around the closing price of bullish Marubozu.
Stop loss: What if the market reverse its direction after printing the bullish Marubozu ? The low of the candle will act as stop-loss in case that happen.