HL2DM Hazard Course : Introduction
For starters, this link is a recommended read.
http://www.hl2dm-university.com/curriculum.php
It covers everything from basic details to advanced techniques about all you need to know in HL2DM. I will just highlight a few important point.
Press shift to run
This is the most common mistake new players make. Unlike Half-life 1, shift is now sprint as opposed to walk. This is important, as you will need it always in fast paced HL2DM. Speed is the key. But do note that sprint is not infinite, as it will slowly deplete as you sprint.
Press g to swap out gravity gun (or gravgun or just ggun)
This will be much faster than you choose them one-by-one from your weapon (wep) list. Again, because speed is the key. Every miliseconds count.
Fight with your brain, not with your emotion
If you are just killed by an opponent with powerful RPG, obviously you do not rush at him immediately after respawn with only default SMG and Grenades. Chances are you will just get yourself killed again. Instead, stay far away from him and start gathering ammo and more powerful weapons to counter him.
Always on the move
Never stay around on the same spot. Given the common response for players who just got fragged (including you), most likely they will seek revenge sooner or later. So dont greet them with red carpet, for they will not greet you with warm hug.
This applies to camping as well. Opinions may vary, but so far I observed you will just get yourself killed more than you can kill.
Dont go for stationary health/armor refuel station!
Options may vary, but my reason is simple. It makes noise (and very loud one) and you need to stand still while using it. This effectively makes you an easy frag for grav-nade, mag-snipe (will explain it later), crossbow and RPG. Dont use it unless you are absolutely sure that nobody is around.
This concludes my brief introduction. May the force be with you, godspeed.

<-- luckily i found it back.. thanks to someone of course..
