If you are a new Glock pistol owner, see;
www.glockbooks.com www.glockworx.com www.glockstore.com www.customizeyourglock.com www.glock.com www.boatmanbooks.com .
3 dot night sights would be a good add-on. Many like the new HD series from Trijicon.
Some say its best to keep the trigger factory stock, others like to convert it to NY-1(the New York State Police version) trigger system.