Day traders are attuned to events that cause short-term market moves. Trading the news is a popular technique. Scheduled announcements such as economic statistics, corporate earnings or interest rates are subject to market expectations and market psychology. Markets react when those expectations are not met or are exceeded, usually with sudden, significant moves, which can benefit day traders.
Once you have a specific set of entry rules, scan through more charts to see if those conditions are generated each day (assuming you want to day trade every day) and more often than not produce a price move in the anticipated direction. If so, you have a potential entry point for a strategy. You'll then need to assess how to exit, or sell, those trades.
Assess how much capital you're willing to risk on each trade. Many successful day traders risk less than 1% to 2% of their account per trade. If you have a $40,000 trading account and are willing to risk 0.5% of your capital on each trade, your maximum loss per trade is $200 (0.005 x $40,000). Set aside a surplus amount of funds you can trade with and you're prepared to lose. Remember, it may or may not happen.