as a left arm finger spinner i can say, use the around the wicket and over the wicket as a weapon more than your stock. i do listen to shane warne, he ses if you force the batsman to open himself out, he is more likely to make a mistake because youv upset his rhythm.
i generaly go for left arm around the wicket which is on the left hand side as the bowler looks at it, and drift it into him.
then il go around the wicket (the right side and leave gaps on mid wicket so i can get him caught behind.
to lefties i revers it and put gaps at cover to make the batsman play against the spin and have him bowled or lbw.
and as a batsman, the best way to conter this is to step to the ball realy real realy late so you know if its spun and how much it has spun then just drive it and nab a quick single.
or sweep him if he pitches it on leg
or reverse sweep him if im tight for runs
or charge him down if i need quick runs.