As far as I'm concerned, the above by Nova reflects almost what I think.
HOWEVER, while I am very partila to the run-and-gun method...the take it slow and search every room has it's benefits as well...just be smart about it when you do it and don't let one person just wander off because he didn't know they were going to slow down and search stuff.
And if you're the Smoker...please, for god sakes, don't fucking just dick around in a terrible spot if you have nowhere to go because you don't want to get shot. If you're in a no-win situation, just go and get your shit killed, because then you or someone else can be Smoker and spawn in a better spot. In fact, it kind of applies to Boomer too...unless you are absolutely 100% sure you can recharge your puke, then don't bother running from hiding place to hiding place just to avoid the gunfire...assuming you survive the initial puke, wait for the Survivors to stop being purple, then try to get yourself blown up on them. You don't get bonus pts for living.
Also, VARY your tactics. Like, for example, I'm well known for ALWAYS dropping down immediately and going to the left on the No Mercy Subway map. That was recently cost us because Nova has a big mouth and said "Faith always does this", so my team got raped right at the beginning. He knew...HE KNEW what I was going to do.
And yeah, the whole stopping after an "event" drives me nutty too. I'm always the guy who says "Let's go, let's go" and I start to feel like an asshole (more than usual anyway)...needless to say, my impatience has led to many of my deaths. I understand stopping to gather your bearings, but also realize that after an "event" is usually the BEST time to get moving as you, more than likely, have killed all the special infected...and the last thing you want to do is give the infected time to spawn and fuck you up again.
And for fuck sakes, if a Hunter pounces a teammate, and you are a bit far away, don't bother running up and meleeing the Hunter, just shoot the fucker. Like Nova said, a few shots here and there aren't going to shit for damage to your teammate.
I'm starting to hate the molotovs and gas tanks for anything other than defending behind you...being the impatient type, having someone shoot a gas tank (especially right before you exit into the forest on that one map in Blood Harvest from the underground tunnels) aggravates me because you just have to wait for the fire to go away, and that is a PRIME spot for infected rapage.
Here's another tip that everyone should know. You can reload while you melee. Try it. It works. And it's essential for shotgun/autoshotgun users, especially if you leave one round in the chamber before you reload so you don't have to cock the shotgun when you're ready to fire. So, SO important.
Don't shoot the car. Don't melee the car. Don't even shoot in the direction of the car. Hell, don't even look funny at the car.