Put the ball as a yorker,just on the batsmen's crease.by this way,he cannot attack.but,rarely can defend and drive the ball,as you said you are playing on county level,follow this trick and keep a fielder on mid-on and mid-off,when by chance the batsmen hits,the fielder at mid-on or mid-off catches the ball.this is the best trick if you want the opponent to defend and stop scoring runs or get wickets quickly.