ultimately long term buy and hold is the best strategy. Mining is a gamble. Difficulty follows the price as long as price keeps going up so will difficulty.

Disclaimer: I mine at home, cloudmine and hold. Because holding is boring for me.

A good mining strategy if you can get hardware at a reasonable price is 30/30/30.
30% of your mining earnings should be reinvested in hashes to keep up with difficulty. 30% hold long term and 30% cash out to have realized profit.

Good luck.