The best way and without any thinking is to just mine as many as you can you never know how many you'll be needing
You'd need a big ass pile of cash to start mining in a meaningful manner now. Those days are a pretty much gone for the little people.
The only realistic way to make Bitcoin that involves mining is mining the right altcoin and selling at the right time. Namely, mining altcoin number "8393589" while its cheap and easy. Wait for the pump. Sell right at the top. Profit.
If you did this with some coins such as Darkcoin, Nautiluscoin, Doge, Monero... and tons other, you could have made tons and tons of money.