Welcome to CS101: Mouse. Here you will learn everything mouse-related to Counter-Strike 1.6. There are quite a few things to be learned, so stick with me. I will be offering suggestions as to what your settings should be, but always remember that at the end of the day it is all just preference.

[In game Settings]
After starting up Counter-Strike, go into Options. From there, select the “Mouse” tab from the menu.


Many of the options are self explanatory, but let us go over them a little just to be clear.

Reverse Mouse: Ticking this option will invert your mouse's up-down axis. Up will become down and down will become up.
Recommended: Off, unless you're Rambo

Mouse look: Mouse look should be checked if you are using a mouse, allowing you to “look” with the mouse.
Recommended: On

Mouse Filter: Mouse filter smoothes out mouse movement. This may sound like a good idea, but it is best left unchecked. Enabling it will only distort your aim, moving your crosshair slightly off cue from where you want it. If turned on, Counter-Strike will calculate all your mouse movements over the last two frames to find an average and attempt to give you a more fluid feel. This means using older data to move your mouse instead of the most up to date information. Theoretically, with mouse filter off, you could also receive a slight FPS boost on lower end systems.
Recommended: Off

Joystick: Enable this if you prefer to use a joystick over a mouse. Disabling Joystick and all it's byproducts can in fact decrease load times slightly, which will be more noticeable on a slower system. This is because your game does not attempt to detect and initialize a joystick at startup.
Recommended: Off

Joystick look: Joystick look is the same concept as Mouse look, except this time for the joystick.
Recommended: Off

Auto-Aim: Aims at enemies automatically. This option is checked by default. Auto-Aim is disabled on most servers as many believe it to be a very cheap feature. This also will hurt you in the long run, not only will your aim cease to improve but those already skilled will find this option to be unhelpful as it throws your aim off.
Recommended: Off

Mouse sensitivity: This option allows you to change your in-game sensitivity, which sets how fast your crosshair moves. While a sensitivity of 5 or below is recommended and generally accepted, your choice is totally dependant on your current mouse and surface selection. Check out GotGear if you are looking for a new mouse or mousepad.
Recommended: Pure Preference