Best strategy is something that needs to be reflected against your goals and ability to take risks. I for example hold approx 70% of my coins and with the rest I am doing day trading. Former gives me security and stability, latter accumulates Eth and BTC. Some trade cycles are medium, 1-2 months, some cycles few hours. It all depends on the coins volume, volatility and maturity. Unmature coins I am willing to let go, just to earn decent profit in the trade. Usually 5-15%. More established coins might even end up to holding, if TA suggests gradual increase in price. If the price is fluctuating, I will sell and buy back later for lower price.
This strategy plus the recent rise of the market has provided me decent profit and increase in number of coins. Suits me as it gives me both stability and excitement.