Budgeting and separate accounts really helps.
We looked at all of our yearly expenses such as holidays, Christmas, birthdays, insurance, new school uniforms, car tax and servicing, new tyres, replacing broken white goods, National Trust membership, tv licence, delivery of logs for the fire etc, etc. Add it all up and divide by 12, then save into a pot to cover those things. Then work out what you need for food, fuel and monthly bills to see what you can afford to save and spend.
Savings (short term cash and longer term into stock ISA) plus the yearly expenses amounts go straight into savings accounts at the start of the month.
The day to day spends (our 'pocket money'- for clothes, eating out, entertainment etc) goes into our Starling account. When we spend from our Starling account it rounds up the pence and pops the extra into a savings account so we can save a little bit extra without noticing. In the account we can look at our spending by type, so it's easy to see if we're frittering it away! It definitely makes you think before spending and we've usually got a bit left at the end of the month now!
Food, fuel and anything we've budgeted for goes onto a cash back credit card, we usually get around £100 a year in vouchers from it. If we spend less than budgeted on food or fuel then it can go into savings.
We're saving for an extension at the moment so we're focusing on building up cash savings at the moment rather than reducing the mortgage or investing. Once we've done the extension we'll direct more to overpaying the mortgage and building up our ISAs.