stopsound - stops all sounds that are currently playing execpt for Mp3`s, bind it to a key and press it often

bind p stopsound

r_drawviewmodel 0 This removes the weapon model, so you get more screen and better FPS, it can take a bit of getting used to

hud_fastswitch 1 This is an Important one it switchs weapons quicker

cl_corpsestay 0 - This makes the dead bodies go faster, so its easier to see proning players

cl_fog 0 - Turns fog off

cl_bulletejects 0 - removes the bullet casings

cl_particlefx 0,1,2 (0 = no particles) This lowers the particles effects and can help reduce lag, if your playing zooka set it to 1 to remove the smoke

cl_dynamic_xhair 0 Turns off animated crosshair

_ah 0 Turns off the help tips

r_detailtextures 0 Turns off detail textures

cl_fps 1 show your fps

net_graph 1,2,3 shows fps and more detailed information about your connection. see below links

http://www.tweak3d.net/tweak/halflife/5.shtml
http://www.dodbits.com/tutorials/netgraph.html