As I was advised, to optimally register the IP with a simplified taxation system for income (6%), do not forget to specify foreign economic activity (although, maybe, not required)open currency and ruble accounts, sign a contract, get money to the account (if customer cannot/does not want to pay in rubles, that is, to carry out the conversion of your Bank) in the invoices/acts of the executed works (can be in electronic form), instantly sell all the currency to the Bank account (to avoid issues on exchange rate differences, etc.), to pay 6% of the income in rubles (plus UST of some kind), to withdraw cash or transfer on card accounts of physical persons with payment "for own needs"