In my opinion you should always have a spinner in the team (just in case) because some online players, in their bid to hit him for 30+ runs, give you 2 wickets for like 15. When in need of wickets, a spinner can be a good tactic. The trick with the spinner is to have fielders in the right places and then deceive the batsman by changing the ball at the last moment. For example if an off-spinenr is bowling to a right-hand batsman and your line is outside off stump and then spinning into offstump or if it's a big turner of the ball (Murali), middle stump. In that case, the batsman is most likely going to hit you straight, in the covers, to midwicket or to the point region. That's four fielders deep. Depengin on the quality of the online player, you can have the fifth one deep as well if he's hitting you to some other place (could be square leg). Remember keep the fine leg fielder inside the ring, even though you might get hit for a couple of bundaries in that region. That makes it six fielders (you can have the fifth one at square leg or deep square leg as I mentioned). Keep the other 3 fielders at point / cover point (depending on where exactly your deep fielder is in that region), mid on and mid off (Note: both of these fielders should be at the edge of the circle, as straight as possible).
Now that you have your field set, and your general offspinner's line set, we come to the actual deliveries. Generally it is better to move the cursor slightly away from it's default position (not left or right) towards the keeper. That is the ideal length (unless he keeps coming down the track). From that position you can sometimes bowl the offspiner (full turn), the offspinner that does not turn (one of the most useful deliveries online) and the doosra but shift the cursor slightly closer to the stumps if you're going to change the ball to the doosra. Bowl the odd top spinner as well but move the cursor quickly to leg stump if possible or middle stump (the important thing is that it should be yellow). If you are sure he's going to hit the ball to the legside, then bowl the top spinner outside off stump (the original line). What delivery you bowl depends on the online player's area of strenght and your prediction as to what the other guy thinks you're going to bowl and then not bowl that!
If he keeps coming down the track, try to get him stumped even if it is a wide and generally move the cursor slightly from the default position away from the keeper. Remember at all times hat apart from the offspinner that does not turn and the top spinner that is outside offstump (if you know he's going to try and hit you to the legside), Never bowl a ball with the cursor not being yellow or light green!
Hope this helps. Also remember that if still you go for a bucket full of runs, then complete the overs by bowling a medium pacer.