Standard Glock triggers aren’t bad, but they’re also not really light or extra crisp. Apex triggers are popular and can be very crisp with a short reset. There are a lot of a brands making aftermarket triggers that can improve the break, reset, and pull weight.
While changing the trigger can help improve your shooting performance, so can adding one of the increasingly common optics out there for pistols. It’s been pretty hard to miss all the optics-ready pistols coming out lately that are just waiting to host a red dot. There are Glocks that have had milling work done to accommodate an optic on the slide, and you can do that with one that is not optics ready. Glock also has optics-ready pistols, such as the Glock 45 MOS, meaning Modular Optic System.
Finally, changing the grip texture on Glocks is another easy and very common modification. There are grip wraps you can add, such as Talon grips. You can even modify the gun directly and have custom stippling added to the grip to make it as grippy as you want. Since Glocks aren’t known for very aggressive grip textures, this is a very popular choice for people worried about having to maintain a solid grip under wet, sweaty, and otherwise stressful conditions.