If this is your first handgun, you should not do anything to improve the accuracy of the Glock. Glocks already come in the box more accurate than many can shoot. The barrel in the Glock has polygonal rifling rather than groves which allows for a tighter seal with the bullet and higher velocity. Most aftermarket barrels are groved. There are however numerous trinkets and other things made for the Glock to improve ergonomics, slide releases, and clip releases. The only thing that I would suggest is that you buy a Glock .357 Sig barrel and shoot the .357 Sig round. In your Glock it has the same power as a .357 Magnum! The .40 S&W is rather short and wimpy. All you need is the barrel, your clips .40 clips will work with the Sig ammo.
Check out www.glockmeister.com
I don't think that they sell origional Glock barrels, but that site will give you lots of info.
Just keep shooting and glad to have another member of the Glock family around.
BTW, I shoot a G19, G33, G20.