Welcome to the Lugerforum Jim.
Luger trigger pulls can be a mystery to most new Luger owners because the trigger/sear linkage appears quite complex to the casual observer.
The first question I have is, Is your Luger all matching parts? If it is a gun that has mixed parts, especially in the trigger linkage, this could be one of the problems... the parts were not hand fitted to each other. Do the two digits stamped into the trigger match the last two digits of the gun's serial number? How about the sear bar? and finally the firing pin? Any differences here can be the root of your problem...
A second issue might be that the gun is very worn and there are tolerances necessary for firing the gun that are somewhat out of specifications.
A third issue could be the extent of sear engagement may be less than ideal due to some previous owner attempting to improve the trigger pull and the surfaces for sear engagement may have been stoned improperly.
All of these issues can be remedied. My furst suggestion would be to disassemble the gun and make sure that the firing pin, sear bar, and sideplate are really clean and well lubricated. Make sure that the spring loaded pin on the end of the sear bar moves easily and is not sticking. And make sure that the surfaces of the L-shaped lever in the sideplate are clean and have no burrs or deep scratches. Then reassemble it and test the trigger...
I remember that one of our members who is a practicing gunsmith once posted the procedure that he uses to improve trigger pull on Lugers... but I don't remember if he actually posted it on the forum or emailed to members who had an interest...
His name is Hugh Clark and he posts under the name of Hugh (member 15). Perhaps he will see this and post some suggestions.
Please tell us about your Luger... and post photos if you can.
Once again welcome to the forum.