The first Support for Nifty looks to be around 18600 levels. In case of that support getting compromised we can expect next lower supports as marked on the chart getting tested out.
Any buy interest around these supports can be traded for quick scalp to above resistances as marked.
I would prefer to short Nifty in case of bearish reversal triggers from Previous closing price levels in the opening.
Buyers will dominate only if Previous day closing is taken on upside then we can expect to sit for Previous day high as a target.