Resident Evil: Operation Raccoon City

This achievement is pretty self explanitory. This achievement doesnt have to be rush because playing through the campaign will get you closer in achieving the achievement.
Going through the game on vertern difficulty will pretty much make you over use the Green Herbs to the point where you can run out. very easy achievement that doesn't really need to be paid to much attention till it pops:)

You can do this while going for the proffessional or veteren achievements but you already know this. therefore this is't much of a guide:)
Also if you playing on Casual or Normal a bit too much, I recommend hurting yourself with a grenade to weaken yourself to use them(only if you really want it done) but it's better if you just continue playing other then hurting yourself over and over for herbs that are just laying around.

Oh yeah, you can check how much Green herbs you already used if you go to your stats. It should be on the section "Globle" under "Used Herbs" .