We have a higher salary level, but we didn't have when we were going through it (but I had returned to FT work with DD in paid childcare after mat leave - we love her dearly but I needed the sanity of the adult world too).
Her creche fees took almost all of my salary.
DH paid the mortgage.
And we split the other bills.
We had a very quiet life for a number of years (which suited us anyway, we were working hard and DD took our time at weekends) - limited visits to cinema/theatre, only the odd night out for pints etc.
We always had a lot of clothes for DD to make life easier to manage - and not be under pressure that the only spare outfit was now dirty and needed to be washed overnight for creche tomorrow...but mostly it was clothes from places like H&M/Penneys etc, and very wash and wear types. I usually stocked up in the Next and other sales for the next 6 months, and would grab things for the following year if I saw useful things at good prices.
For our own clothes, we have always tended towards classics rather than high fashion, and I will mend things to make them last longer. And I tend to dress in layers, so have things like vests and thermal leggings to allow clothes be more useful for longer in the year. We also get solid shoes, which get heeled and soled as needed and last years and years, not a season or 2. And I also will buy in sales/clearance, and in charity shops too.
Use loyalty schemes in supermarkets, and coupons and special offers on things we would buy anyway. We have always tended to cook from scratch a lot, rather than convenience food, and I often buy ingredients from ethnic stores (Asian supermarket, Italian deli etc) and local stores (butcher, fishmonger, veg shop etc) for good deals. I bulk cook at times, getting offers on meat etc and then making a few weeks worth of Shepherd's pies or Spag bol sauce or Chicken curries, and freezing those in single or double portions for midweek dinners. And most of those meals have a LOT of extra veg in them. And if I see yellow sticker items that are still ok to eat, and that we would eat, I buy those and put them in the freezer (or change the meal plan for that evening). And yes, I tend to plan meals at least roughly for food shopping and planning purposes. Including "MN Rubber Chicken" weeks - roast on a Sunday and various leftover meals for a few more days.
We shop around for insurances etc. We pay off credit cards every month so don't have interest to pay on those. We have tended to buy cars with cash not loans, and buy as small as we can manage with and generally older rather than newer - once they take what we need and will run reliably, then that's the important thing. We keep on top of maintenance, so regular cleaning and painting and servicing of the house/cars/appliances etc rather than major repairs or replacement costs. And we would do a lot of those jobs ourselves where we could (even things like tiling our first house, and making a lot of the soft furnishings on the sewing machine ourselves).
We both have savings which come directly out of our salary before hitting our bank accounts. And others set up to happen every month. Which we had done from as soon as we started working. I have a habit that, whenever I get a promotion or payrise, I give myself a treat with the first paycheck after that, and then increase my savings amount as I was managing on what I was getting before - before I get used to having more money to spend.
I have now developed a takeaway coffee habit, but I was a long time just using the kettle at work. And I still bring my lunch with me most days, only going to get a sandwich or something once a week or so as that is so much more expensive.
We only got sky a few years back when we changed broadband providers. Before that, we had terrestrial tv and the freesat channels - but there was plenty of choice with those. We've had Netflix since it started in this country, but that was a lot less than Sky per month.
Our holidays have tended to be a lot cheaper than many others - self catering, often in this country or getting the ferry to the UK rather than flying to the sun, and not tending to be major party animals but more relax with books and walking and nice meals types of breaks.
And when we were less well off financially but had more physical time to do it, I had an allotment where I grew a LOT of our own veg and soft fruit. That did cost me some money, but I more than saved overall when the harvests came in.
Part of what really helped was that, as interest rates started falling in the last recession, while DH's job was uncertain he still had it and we kept the mortgage repayments at the original levels (the plan being to drop to the required new levels if we had to) so the extra money went straight off the capital every month. And we would put any bonuses DH got, and occasional lump sums as my savings built up, into that as well - once we still had enough savings for emergencies in our accounts.
So lots of general frugalness and watching where our money went and trying to keep all costs low, savings before luxury, and some luck.
The past few years, we weren't as focussed on it as salaries improved, time decreased, and life has been too hectic. But interest rates had never really risen again so the extra money was still going in all along to pay off capital and we had made such a good start (which really reduced the interest to be paid on that part of the capital repaid early!) that we finished paying it off at the beginning of last year without pushing ourselves hard - 7 years early - but we could have paid it back about 2-3 years earlier if we had pushed but there is no real interest to be earned anywhere else so we decided to just enjoy life a bit more.