I'm a fast bowler myself, bit I've always felt that for spinners, length is the key. Bowl short and the poorest of batsmen (and I include myself in this

) will have plenty of time to pull or cut you away. Only bowl short if the batsman is coming down the wicket at you (and I mean he's coming at you that ball). This will make it much trickier to hit and brings stumpings into play.
To be honest, all spinners get slogged sometimes. Shane Warne may have taken the most test wickets, but he's been hit for 6 for time than any other bowler too. The key is to get on top of the batsman and keep him defending.