Use of tactical lights, laser aiming systems....
I'd consider a white light or light/laser if you feel you can add it to your carry pistol. If it has a 1913 rail, then you could add in on.
In my opinion, a green laser system with a bright light/strobe is best. Viridin markets a well made unit that fits most brands(M&P, SIG-Sauer, XDm, Beretta).
Some LE officers & armed citizens like the flashing Lasermax red laser that fits in the pistol guide-rod. The human eye is drawn to movement & the Lasermax battery lasts long in most conditions, but I like CT lasergrips & green lasers.
There are holsters & gear available for pistols with lasers/lights. Safariland, Blade-tech, COM Holsters, Galco, Unkle Mikes are well known brands.