If I make money on crypto currencies. How do I avoid as much tax as possible?
Firstly, tax imposition on cryptocurrencies primarily depend on the laws you have in your respective country. All countries have their own stand against the regulation and tax imposition on cryptocurrencies; your obligation now is to be responsible and diligent enough to at least check if your country approves on cryptocurrencies. But in general, I believe that cryptocurrencies in general aren't taxable due to their decentralized nature which makes them the perfect medium for transactions.
If indeed your country requires to pay taxes related to crypto currency, pay it.. and no need to avoid it.
And if indeed your country doesn't requires to pay taxes related to crypto currency, yeah.. of course it's ok if doesn't to pay for it. But if your crypto's incomes is very high, i think you've to pay for it.
which's important.. be a good person / a good citizen.
Yes, it really depends on the country's law regarding cryptocurrencies. Just to add, if cryptocurrencies would be taxable then expect prices to decrease on a certain level. The prices also may be controlled in some-point, which makes it no different from other investment options.