To buy or sell a coin I like to do Technical analyses also. With the help of Technical analysis, I can easily find out the support/resistance zone. Support is the place where a lot of buy order is available and resistance is the place where most of the people sell their coins. Trust me, It works most of the time. Besides support and resistance, I like to use some indicators to identify a good entry. Among them, EMA, MACD, RSI, Fib retracement, pivot point, super trend, etc are mostly used by me. You can easily learn about those indicators by using youtube, there are a ton of free videos available regarding that indicator.