First thing first, the spelling
Portfolio and not "protfolio". Not sorry for being a grammar nazi
Second considering cryptocurrencies to be one sector as per popular demand and not what I prefer, this approach can be used for managing different coins. However my experience has shown me that investing in altcoins is a waste of time and money, however big or small it might be. Thus if you want crypto in your portfolio, keep a 100% Bitcoin, the long term value is way better than any altcoin.
Next to manage the portfolio add in more sectors
different from crypto, like stocks, commodities, bonds, metals. Do not try to put in more money into altcoins, but into sectors that have been known since centuries to give returns. Although some people may disagree, risk management is better done in this manner.