Two knights defence - Ulvestad variation
Studying openings, their thematic moves and ideas behind them pays off though it is a rather long run. Getting an advantage from an opening is stimulating but if you don't know the ideas behind the opening and play some tactical variation it's easy to go wrong.
I came to like two knights defence in the Italian game since it provokes white into action and then they may be surprised how passive their position gets. I used to play Polerio variation (knight to a5 on the 5th move) but often didn't manage to transform the original pressure into a victory, therefore I switch to Ulvestad variation and, after a few tries, finally a rewarding win.