Advise you to get some snap caps and do a lot of dry fire practice. This will not only smooth out the trigger, but will also allow you to learn control of the trigger. The primary cause of low & left in right handed shooters is trigger control, while lefties are usually low and right. In addition, grip and stance play a more important role in small autos than in their larger brethren, so you need to work on those too while you dry fire practice. This diagnostic chart should help. Flip it horizontally if you are left handed.
BTW, 98% of all the low and left issues are shooter induced. Even though the 709 has sights that are adjustable, it is best to shoot a lot of different ammo types, brands, bullet weights, to find what shoots best in your pistol with you doing the shooting and then make whatever minor sight adjustments you need to make.
Don't worry about finding the "magic bullet" SD round. The sad truth is that just about all the premium brand SD rounds perform about the same. The only differences are usually in the tradeoff between penetration and expansion. Rounds primarily aimed at home defense markets will feature expansion over penetration in an attempt to lower risk of collateral damage (like the kids sleeping in the next room), while rounds aimed at the LEO markets will feature penetration over expansion to increase performance against barriers (like shooting through a windshield, or car door). The solid cooper bullets may be the only exception, but as of right now I think the jury is still out, not to mention they are expensive.
