I have Trijicons on my 19. Meprolights are good too. A 3.5 lbs connector will make a huge difference. Google the 25 cent trigger job for Glock. If you want to spend the money, buy the $125 trigger from Vaneck on line. It's already pollished and ready to go. Just drop it in. If you are comfortable with doing it yourself it costs about $13.25 or there about.
3.5 lbs connector = $10.00
Wolf reduced power striker spring = $3.00
$0.25 trigger job = ...
The best advice is to dry fire and learn the trigger. IMHO the stock Glock trigger is a little stiff but not unmanageable. A gun is a tool, like any other tool. Have you ever used a hammer and thought, hmmm...what could I do to make this hammer better. Chances are you've just grabbed the hammer and banged away. Just bang away with your Glock.
This is a sensible post, good advice. It is something many, including yours truely, discover eventially, but it seems to be just a matter of how much time and money they spend before they discover it.
It really boils down to what you want to do with the pistol. If you want to compete, then a custom trigger may be well worth the investment. I personally went with one from glocktriggers.com over the vaneck.
Two other mods you may want to look at are a steel guiderod, and some grip tape. You can buy the 3M stairs tape and make your own, or buy the same stuff pre cut.
As far as sights, I have and really like the Warren-Sevigney tactical carry with fiber optic (but they do have a tritium version) Glock sight set from Dawson Precision.
Other than that, the best thing you can do is go buy a case of Ammo, and shoot a lot.
Good Glocking,
WG