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
but to me if you are doing trad in such item about which you have some good knowledge and you also have good experience and skill then you can really make a successful trade.