I once demonstrated a trade procedure for a friend who was new in trading bitcoins. All i did to make the trade successful was to introduce him with localbitcoins traders in our region. And he said that was cool after successfully trading.
that is a strange question, but anyway,
i think that successful trade is when you earn profit, so you should sell any coin for large price and buy them for smaller
While I agree that the whole essence of trading is to make and maximize profit, I must differ from the idea that a successful trade is when a trader makes profit, because profits can be made even in error or gambling, but the knowledge and ability to manage the capital is what sets one trader part from another and just like Warren Buffet pointed out, " More important than the return on your investment, is the return of your investment"