Always do a research first on the coins you want to invest and hodl, Coins with active developers and supportive teams will surely stay long in the cryptomarket. These developers keep upgrading or innovating their coins to meet the challenges that lies ahead thus keeping also their coin on the top of the market.
Projects that are working products and real uses, will certainly always innovate and develop projects. Then the analysis is very important to determine the right time to sell and hold. By understanding the roadmap, we will also find out the team's seriousness in developing the project.