The Glasgow giants recorded a 2-1 win over Barcelona in the group stages of the competition last season, but the Spanish side will enter the match as the overwhelming favourites at Celtic Park.
"We will go and enjoy it. We were a bit unlucky in that game against Milan, we didn't take our chances. I don't think we will have so many chances against Barcelona so we need to be more clinical," Samaras told reporters at a press conference.
"If we have the chance, we need to put it in the back of the net if we want something good from the game, like we did last year. We have to stay focused, try to minimise our mistakes and try to play to our strengths."
Celtic opened their Group H campaign with a 2-0 defeat to AC Milan.