Buy more when the price is low and sell low when the price is high. This is how portfolio can be made stronger with time. To achieve this pattern on trading one need to be very careful watching the market fluctuations. People always get into panic state when the price is high and tends to buy feeling they're missing the opportunity. Same as this sells at a low price feeling the market might crash even further. So, trading or holding needs to be done after good study.
In addition, this technique also makes us not hesitate to sell the assets we have. because our goal is to increase assets, not to make them less. however, the problem is, many people do the opposite out of panic. buy when the price is pump, because they are seeing the trend going up. however, sell when the price is down, because they panic. however, it is very difficult to do this correctly even though it is very easy to understand. only, if one's goal was to increase their assets, then it might be easy for them.