Market is down at present and i think invest as much as you can as after correction phase prices would surely surge and high profit is expected on return.Holding currently is another good planning to earn a considerable return as per your planning.If you sell your investment due to low prices you would not be able to receive much profit.To me currently both Investing and holding strategy are inevitable...
I also think that the strategy of holding coins is now the best. Because price on all coins is very low, and sell now is stupidly.
Of coarse holding and buying more is the best thing to do in current scenario. I dont get people that sell their coin holding when the market is running at its all time low and then later cry cause of loss. Patience is the main thing that one must have when he is not just investing or trading in crypto market, but every other asset market such as stock and gold. As long as you hold coins and dont sell them for fiat money, you are never in loss. Its just matter of time when you will be in profit again.