If we are talking solely JC2 then all I use is unlimited ammo/grenades. I balance this out by playing on the hardest difficulty. The game seems like a John Woo flick to me so I pretend I am (Tequila?) Chow Yun Fats character in Hard Boiled. Highly recommended movie in general but especially if you love JC2.
As for cheating in general I do what will allow me to maybe complete a game in style sorta speak. Take for example Oblivion or Fallout 3. The cheats used on those are mods to enhance the game. No god modes or anything but stuff to smooth out perceived design flaws. No money cheats as they are well balanced economy wise but I will use level up mods or mods that improve what the stats do. Increased weight capacity or more HP per point of endurance.
I buy a new game each week so have limited time to play them all. It sometimes sucks being a hardcore gamer. I have beaten maybe 15 games in my 30 years of gaming. Diablo2 and Xcom UFO Defense being two I remember best. I might as well say Borderlands now as well as I am maybe 5 hours away from my first playthrough completion. This is without dlc addons.
I try not to use god mods unless the game is rediculously underbalanced. Did that for some Colonel in JC2. 3 rockets to the face and he wasn't scratched. Died before he was taken below 90% health. Turned on god mode and spent 10 minutes killing him and his cohorts. I'm pretty sure he was bugged but didn't catch his name. Was too ****ed at the time. I have killed other Colonels no problem.
Before giving a dissertation I'll just say I try not to use cheats unless I deem them necessary for balance or in JC2's case pure fun factor.
/salute