Because we are currently in this weird no-man's-land where we have purchased one house and paid for it, but haven't settled the old house yet, we are currently paying two mortgages (plus the Brunswick house, but that's cash positive) and holy crap, things are tight. Here's my tips on being super scringy.
Don't go to Kmart or Target. Seriously, I walk into those places looking for a pair of socks or a toddler's singlet and come out with a plant pot, dry shampoo, a new doona cover and some glitter crayons. If you're really serious, basically just avoid them completely. If your weakness is Bunnings (me) or Priceline (also me) or that cute deli with the good cheese, the same thing applies. Don't go there. Or at least make a list of all the stuff you need, then do a big shop at once. You still feel like you get to buy heaps, but it's not crap you don't need.
Track everything. I've heard this advice before and frankly, the thought of putting every expense into a spreadsheet sounds heinous. Luckily, I found Pocketbook, which links to your bank account and categorises all your expenses and incomes. So I can see specifically how much I spent on Xmas gifts last year, how much our utilities are each month and what percentage we are saving (or not).
Do a meal plan. I have a love/hate relationship with meal planning... I like to think of myself as spontaneous and a fabulous cook who can whip up a delicious and nutritious meal from a can of chickpeas and a carrot, but alas. I'm more of a "Holy crap it's 5pm and I need to go to the supermarket... let's have eggs on toast, guys!" The truth is, meal planning stops you from buying random excess junk (see Kmart and Target, above) and only buying what you need.
Do free or cheap stuff. This is especially good when you have kids. Seriously, my kids are happy with a bit of open space and a stick. Meet your mates at a playground with a cafe, get a coffee then let them go wild (the kids, not your mates).
Don't buy crap. This can pretty much be applied to everything, but it is especially noticeable with clothes. That $10 top? It will fall apart after one wash, pick up a permanent stain and shrink to a size four. Save up until you can find something that is well made and will last a while. I have a Country Road cardigan that I've have for six years and it still looks new, but I can't say the same for anything I've bought from the el cheapo stores.
Join things. We have a family membership to both the Melbourne Zoo and the Melbourne Museum. The memberships were exxy to start with, but we go to the zoo and museum at least monthly, so it works out way cheaper. Memberships like this make good Christmas presents from grandparents too!
While you are joining things, dig out your library card. The library is ace! If you churn through heaps of books (ahem), you can reserve or hold them online, then go and pick them up in person. I always grab heaps of cookbooks when I'm there, cook nothing, then take them all back. Libraries also have heaps of kids stuff on too - story time, author events and homework clubs. Get onto it.