I was a debt adviser for a long time and it really opened my eyes. I check our bank accounts pretty much every day to keep track. We have a spreadsheet for outgoings but for things like shopping / gifts / meals out it's very much a ballpark figure. So, some months we may not eat out at all, whereas others we end up being out twice a week every week, but it balances out in the end.
We're lucky in that we both earn a decent salary (though DH earns A LOT more than me), so we don't have to be too strict in general. When we have a goal in mind (big holiday, newer car) we will always save rather than use credit (unless it's financially more sensible to get a 0% credit deal and keep our money earning a bit of interest in the bank).
We don't have kids yet (about to adopt) so we have a big cushion of ready cash in the joint account we've been building up separate to our savings. We've done this by:
'Eating the freezer' for a week or two (still buying odd fresh bits of course)
DH has joined a cheaper gym, both reduced phone contracts
Refixed mortgage rate for next 5 years for stability (1.84%) - we ALWAYS go via a broker like London & Country to get the best deals
Always switching gas/elec to cheapest supplier
As a PP mentioned we also get the Moneysavingexpert email and the site is great in general
Buy Birthday and Christmas presents year round - have a box in the cellar we put bits in as and when we see bargains / Jan sales also for cards/wrapping paper. This works really well for us and we don't then have a big 'shock' expense at Christmas