A crosshair has one job: preserve information
A competitive crosshair should be visible without covering the target. Test it against bright sky, dark interiors, effects, and the colors that appear most often in your game. A color that looks clean on a settings screen can disappear during a real fight.
Start static and simple
Dynamic movement or firing feedback can teach behavior, but it also creates visual motion at the center of the screen. A small static design is a strong baseline for judging placement. Add a center dot only when it supports the aiming task rather than filling the gap you use to frame a head.
Validate at real distance
Test close tracking, common head-height angles, and the longest range where precision matters. Keep the design for several sessions before changing it. Crosshair tweaking feels productive because feedback is immediate; performance changes require a stable comparison.