The only modification I'd recommend for a lighter trigger is a "minus" connector. Other modifications include stronger trigger springs and lighter firing pin springs but if not done correctly they can make the gun less reliable.
Here are some detail strip resources if you need them, you'll need a 3/32 inch punch like the Glock Armorer's Tool:
Make sure when you reassemble the frame, that the locking block pin is in the frame before you install the slide stop. This will ensure that the slide stop spring goes to its correct position, under the locking block pin, to give the slide stop spring its tension. If you install the locking block pin after installing the slide stop, you may damage the slide stop spring and the spring will not be in the correct position, resulting in the slide locking back with ammo still in the magazine.
On the following page are some Glock Armorer's Manuals, just scroll down to the "G" section. I learned from the Update Manual and 2009 Manual. The 2009 Manual has a few pages missing, but that info can be found in the Update Manual as well. http://stevespages.com/page7b.htm