Agree in writing what precisely maintenance covers and doesn’t cover and how you will split other costs. Even if things are amicable now, kids get more expensive as they grow and if/when new partners come along they will have opinions about finances.
Easy to get lost in admin so build a routine for looking after yourself and your health.
Budget below your means and keep a slush fund for emergencies. Aim to build up a month as instant access savings and put as much away in an isa as you can.
Go over your accounts and balances daily until you instinctively know what’s in your funds at all times.
Diarise everything - know when big bills are due, MOT, house insurance, utilities etc
Get the best deals, swap supermarket, use loyalty points, get meerkat for best insurances and then cheaper cinema tickets, get on airtime, etc etc.
Learn how to do stuff yourself and have a good basic toolkit in the house. YouTube it before calling out a costly professional.
Teach your kids about money. If your ex or family don’t cover this, take your kids shopping for your and eachother bday and Xmas presents - when they are small get them to pick it out with you, when they are bigger send them down the high street.
most important thing I’ve had to learn is to ask for help. Don’t take the piss but if your best friends husband is a plumber, ask in exchange for looking after their kids one day or similar. Also, research (mine) shows that if you ask a man if you can borrow his power tool to hang a shelf, that man will immediately offer to hang the shelf 😂
Use the school second hand sales or Facebook group where possible. Same for all those hobbies.
Get the kids involved in tidying up after themselves and as they grow, help fold and put away clothes, put away the shopping, empty dishwasher, etc so it’s not all on you.
Yes to the toast and milk tips above and to add to that, have a great pancake recipe to hand.
Finally, decide your tolerance levels. Do your kids need the tidiest house on the street Saturday morning or do they need to be with you snuggled up in the sofa with a movie.