Body
This section covers keybinds, posture, sleep, diet, and exercise
Keybinds
Most afps players use the keys around their movement keys for weapon switching. if you use WASD: Q, E, R, F, Z, X, C are your primary weapon keys. Some players use mouse buttons as well, while other players prefer to keep binds off the mouse to avoid affecting their aim. As you bind your keys, consider putting the most important weapons on Q, E, and R (rocket, rail/pncr, LG/shaft). Also consider how weapon combos work in afps. Since the weapons have no reload other than the time it takes to fire, high fire rate weapons usually start combos, and low fire rate weapons usually finish them. For example, shaft to pncr or shotgun: high fire rate of shaft lets you swap to pncr or shotgun immediately for a final burst. For the low fire rate weapons you use to finish combos, it might make sense to use a key or button you can access while strafing mid-fight. In practice you can hit a lot of buttons while still maintaining a dodge, so don't overthink it before you get used to something. Above all, make sure your keybinds are comfortable for your hands.
QCP Keybinding QC https://www.youtube.com/watch?v=oRji_A6tnZ4
Frothy Keybinding QC https://www.youtube.com/watch?v=dmyHjnnufOc
Quake Live Basics: Control and Configuration https://www.youtube.com/watch?v=P-jumMdn1VE
Posture
Before you spend money on a fancy mouse/pad/keyboard, make sure you have a sturdy desk, ergonomic chair, and a monitor with good height adjustment. For picking a mouse, the first consideration should be posture as well: what size and shape fits your hand best and doesn't hurt your wrist after a long play session.
Table and Chair Posture https://www.youtube.com/watch?v=UW_z6bCy1ZI