One of my favorite tricks is the blocking trick.
if you block successfully 3 times in a row, your next clean shot will do double or triple damage to your opponent. this is especially effective when you are beginning to lose a fight.
Block 1,2,3 hit, block 1,2,3 hit, and so on until you destroy your opponent. Also, most newbies will think they have beaten you so they will be more aggressive and block less, leaving themselves open for the final shot.