Sell when the price goes up and stalls Buy when the price goes down and stalls or follow Jack Hershey's advice. If you decide for the latest, better hire an arqueologist to help you decifer what he says. It's all written in code
Use fixed range charts so that you are always looking at the same geometric configuration. Dynamic charts can be very deceptive as they will cram the daily range into the available space on big moves which distorts the angle of your trendlines or whatever indicators you are using. When your charts are always the same you can then, eventually,judge when you have a trend with your eyeballs. If you want to use an indicator the macd is pretty good as it is absolute rather than relative. A lot of people use ADX but these are only giving a number to what you should be able to see with your eyes after some serious screentime.