Hi Celast! Sorry i missed your post, i was away at a wedding all weekend, picking bread and pastry off everything so i could get something to eat!
The others have described what i do very well. All packaged stuf is easy, it's on the packet in terms of how many grams of carbs per 100, so I only have to work out how many 100's I'm eating of that to see my carb intake. For loose stuff, like veg or fruit, I just used to google "carb content of..." and you'll see a dozen sites giving you how many carbs in everything. So i know new potatos are 15 grams of carbs per 100 grams of spud, my 3 very small spuds come to about 100 grams in weight, so that's 15 grams of carbs. I say used to, because after a while you get used to how many carbs are in everything so you don't need to do the sums. In fact, I know how many carbs are in every meal or snack I have nowadays so don't have to look anything up hardly - only if it's something new. You'll soon get the hang of it and see how easy it is.
By the way, I'm normally nearer 150 grams per day than 180, but as I'm not trying to keep to such low levels as others, i don't need to be quite so precise.