I recently started tracking my spending in a fair amount of detail.
Every few days, I download the statement for my credit card and import into a spreadsheet which calculates how much I've spent per day so far during this month and how much I am allowed to spend per day for the rest of the month in order meet my monthly savings target - there should always be something left over for unforseen expenses.
My daily budget starts off at roughly 3500kr or 20 euro/day. It goes down or up as the month progresses, depending on how much I spend. Right now, it's down to 2700kr... sigh.
The daily budget doesn't include fixed costs like my mortgage or utilities, I account for those separately. This is just petty cash for food and clothes and socializing. It's not a lot, but if I don't go to the bar too much it's doable.
Today I spent roughly 3 times that at Bonus. Ouch!
On the other hand, I probably won't need to buy meat for about a month, so that's not too bad. I'll still probably allow myself the luxury of a beer or three at a bar this weekend. :-)