I don't know what is blackcoin so that I could have an opinion on it.
Maybe the most consistently rising altcoins for the last three months (I arrived in the crypto scene in 2014). Presently #9 at coinmarketcap.
The spirit of my plan is also that you start selling only after bitcoin/whatevercoin has become a significant part of your portfolio. Then periodic selling also satisfies the Kelly criterion.
I'll take a look at this Kelly criterion. I will start to cash out at 10 % once 100% of my amount would allow me to pay back my expenses. Then at each doubling, I will cash out 10 more % until my initial investment is paid off.