I take on a more casual mining approach, I use just my 2 existing older cards, HD 7870, for mining various CryptoNote coins.
Electricity here in Greece is a little cheaper, on my current power plan its 0,077/kWh at day, and 0,066/kWh at night, so if I keep my PC running 24/7 for mining, it's about 10 of electricity per month.
Even with low crypto prices I mine about 1 per day so the electricity from the PC pays itself after 10 or so days.
But I think that the best strategy IMHO is to hodl. Keep mining and let those wallets fatten up
