Let me start off by acknowledging what a smart reader I think you are. The reality of the situation is that Call of Duty 5, just like the previous four before it, is an extremely linear game. It'd be a waste of both my time and yours for me to sit here and tell you what to expect next, especially considering the fact that there are FAQs out there that have already wasted their time doing such a thing. Instead, I'd like to guide you through what to expect in the game and how to deal with the most difficult situations presented.
I love the flamethrower in this game (probably a reason they don't let you keep using it all the time). It's both brutally effective, and really, really cool. One of the few times where two such things come together in such a great way.
As such, you should use the available flamethrower weapon to the fullest extent that you can whenever the opportunity presents itself in the Call of Duty 5 game.
In any level you come across them, MG Nests and crowded grassy situations should optimally be the best times for you to break out that powerful flamethrower weapon and start lighting everything you possibly can on fire to defeat enemies and clear out the field so you can move ahead.
Tanks are your mortal nemesis in this game as a ground troop. Basically, if a tank shows up, run as quickly as possible to grab a panzershreck and take it out.
The tank not only boasts an incredibly powerful cannon, but also a secondary machine gun that will gun you down as fast as you can make it up to the tank. Don't bother shooting at the tank with anything other than the rocket launcher - nothing else will put a dent in it (with the exception of levels where you are in a tank yourself).
For more vehicle warfare, check out the Vehicles Challenge that's available within the game. To learn about tips on using buildings, grenades, mortar, and other weapons, continue reading the second page that will guide you through each element of Call of Duty 5.