You need to set your controls, advanced controls and audio setup when playing Point of View for the first time.
Point of View is prepared to play the Half-Life's soundtrack.
Some enemies will be surprise when they see you or too scared to attack you immediately, use this to your advantage.
You can't pick human ammo.
Your weapons make sounds when idle.
Useful ammo is not very common.
When going on the manta (Xen flying manta) the door at the top doesn't open and you get stuck or you just get stuck. This is a Half-Life/system related bug. To bypass it try this:
Load a previously saved game and try again.
Load a previously saved game before entering the map where the bug happens and try again.
Try to go back to the previous map and then return to the manta map and try again.
When changing from map A to B, Point of View makes Half-Life exit to windows. Update Point of View to version 1.1 and try again.
On the tank area, sometimes, the garg doesn't destroys the tank after you use the key card on the door. To bypass this load a previous saved game and don't go directly to the key card location. First, go to the machine gun, kill the grunts and then go to pickup the keycard. This will give the time needed for the garg to move to the doors without seeing the Special Forces.
Very rarely the doors don't open because of a dead monster near them. To fix it explode the monster or load a saved game before the killing the monster and try again.