Wear good hearing protection and shoot outdoors if possible. The CZ-52 is loud, and the muzzle blast with some of that 7.62x25 ammo is pretty stout. In and indoor range, it can make you start flinching pretty easily.
The sights on the CZ-52 are typical service sights of the period, in other words they suck for paper punching. Take your time with aiming and concentrate on sight alignment.
The triggers aren't all that bad. Heavy, yeah, but you're probably loosing alot more in the way of groups to your sighting. Over the short sight radius of a handgun, even the smallest error in sight alignment is magnified a great deal down range. Focus on the front sight only, and don't shift focus to the rear or target.
Basically take your time and really concentrate on fundametals.
It'll never be a tack driver, and alot might have to do with what ammo you're shooting, but generally you have to really concentrate on the fundamentals with these to get anywhere with them.