moving averages take a look at TSLA for example, the 50 day moving average for TSLA is about $256 and it acts as resistance so it's a good short opportunity and if it pushes through that resistance then you would cover your short
Depends on how aggressive or conservative you are, if aggressive you stick to Price Action alone and if more conservative you add fundamentals like 0% Dividend, Analyst Recom. Hold to worse, Price $15-50, Sectoring by Industry Groups through Barchart and find something declining in overall Industries, don't want to get the worst of the worst as they might be bottoming soon. Keep track of dividends so you don't end up paying them. Finviz is excellent charting for automatic trendlines that is free if you don't have it on your charting software. Check out AEGR, it certainly more near lows than highs, Hitting down sloping trendline, so it be cheap sell, price either holds or take quick loss if punches through, but always make sure you have studied the instrument well as each stock has a personality.