It depends what I'm trying to do. I'm not a huge spinner of the ball so that may also effect my line.
Right handersI'll start off full and outside off stump, tempting the drive and trying to get one to rip early in my spell to get it in the batsman's head. If there was a Left Arm Over bowler I simply aim to pitch it in their foot hole.
If it's not turning big or I'm trying to build pressure I attack the stumps - you miss, I hit.
Left handersI always come round the wicket to lefties.
On Saturday I was bowling mainly at middle & leg as it was straightening. Make sure you don't miss it batsman

I also use the on/just outside off line to lefties. If it goes straight on then the stumps (and therefore LBW) are in play, and if it turns the keeper and slips may get busy.
SummaryI've got a handful of deliveries I use. The off break, the arm ball, the quicker one and a wrong'un.
I start my spell by just bowling offies (my stock delivery) and once I find my rhythm/line I start sending the variations down. If you can beat both edges of the bat it will get in the batsman's head, but it's not worth giving away freebies trying it too early in a spell.
I've found the key is to bowl the same ball most of the spell, with variations used as a surprise ball. Too many young spinners try to bowl a magic ball every delivery, where a consistently probing line is more effective as it builds pressure and makes the batsman try something different. I'd rather bowl a boring 0-25 off 10 than a 2-63 trying all my variations in every over.