I also recommend you checking out A Slob Comes Clean on YouTube. Dana really gets it and there is something very warm and down to earth about her.
The main thing is decluttering. If you have too much stuff, it's always going to be fighting a losing battle. I have two DDs and we just seem to accumulate clutter. I started with choosing 10 things every day to throw away or drop off to the charity shop. Little and often is the key, if you do a huge decluttering session you can be left with an overwhelming amount of stuff that you then need to do something with. One bag of things you have decluttered is easy to take to the charity shop, or it fits in the bin. I don't bother selling things on, the focus is getting stuff out of the house as quickly as possible.
If you can hire a cleaner to do a deep clean for you, that will get you into a good starting place. If you can't, then dedicate a day to it and get things clean. After that, it's a case of keeping on top of it.
For me, I really hate cleaning and housework. But I realised I was letting it pile up into a big job as I was putting it off. A little bit every day has genuinely transformed how I feel about cleaning as it's never a whole-day job so it doesn't get overwhelming.
Things that have helped me are:
Having a routine and setting myself recurring tasks in my phone calendar that I then tick off.
Every evening the kitchen surfaces and dining table get wiped down, the dishwasher is put on after dinner and a load of laundry is put on. You can put it on a delay timer to be clean by the morning but I just get it on a wash and leave it til the morning as I don't like appliances running when we're all asleep. While I'm doing this, DDs tidy the living room to make sure all their toys are put away (they are 7 and 4 so they're capable of helping out and know for example that dirty clothes go in the laundry basket and not on the floor).
Every morning I empty the dishwasher while I'm waiting for my coffee to brew, make the beds and either put the washing in the tumble dryer or hang it out to dry. Sorting one load of laundry a day means it's never a huge job.... it's just folding and putting away one basket of items.
Then I have tasks set in my phone so I do a minimum of one job a day e.g.
Mondays I change the beds
Tuesdays I hoover and mop all the floors
Wednesdays I empty all the bins
Thursdays I declutter one area
Fridays I dust everywhere
Saturdays I clean the kitchen
Sundays I clean the bathroom
I also have taks set in my phone that recur monthly, or every few months e.g cleaning windows, cleaning fridge and oven, washing the car, running a cleaning cycle on the dishwasher and washing machine etc.
Basically everything is automated onto lists that I then tick off. It helps keep me on track and gives me a sense of accomplishment ticking things off.
But the main things are really decluttering, making sure everyone including children help out and doing a bit every day.