Great topic OP- really helpful for lots of us.
Another vote for not having a credit card. I don't have one either.
Don't just shop around on price comparison sites for electricity, gas, phone and insurance now, make it an ongoing thing and do it every six months.
Organisation is your friend. It's not just meal planning, you can do it with most aspects of your life. Clothes, for instance, are something you don't need stacks of if you plan for what you need. Buy dried beans rather than tinned ones and plan to soak them the night before.
Be ruthless about looking after what you have. I found that making Friday nights non-negotiable shoe polishing night extended the life of shoes by at least double. Sew on buttons as soon as you notice they are getting loose, if you notice a small hole in clothes, stitch it up before it becomes a large hole. Reinforce the knees of your children's trousers on the inside before holes appear.
When I hit my personal downturn in circumstances, I cleared out a cupboard and used some of my very precious small savings pool at my local Chinese superstore, buying things such as 5 kilo sacks of rice, dried chickpeas, dried beans and flour, a 5 litre bottle of sunflower oil, 5 kg sack of sugar, catering size clingfilm, 5 litres of vinegar, a 5 kg sack of bicarb and 2 kg of pasta, then (and this is pretty crucial) reducing the amount I spent on groceries each week to account for the savings I made so they weren't "lost" and I was able to replace each of the bulk goods when they ran out. I also bought a cheap breadmaker (ebay!) and save a bundle making my own bread. This way we still eat excellent quality bread but pay pennies for it. I am starting to learn to bake sourdough bread without the machine, but it's still as heavy as a brick and I don't want to feel deprived of good bread, so the breadmaker still sees lots of use!
Reduce the amount of meat you eat, and plan your meal around the carb in the meal instead of the meat. This means meals are just as filling but much cheaper. For example, have one meal where the main ingredient is potatoes (such as jacket potatoes or shepherd's pie), one rice meal, one chickpea meal, one quinoa meal, one meal with beans each week. Use meat is a flavouring, and schedule several meals without meat.
I make my own soaps with cheap bulk olive oil and instead of buying a lot of expensive cleaning products, use vinegar and bicarb. I bought 5 litres of cheap (horrible!) vinegar at the Chinese supermarket for £1.50, then fill a spray bottle with half vinegar and half water. It's as good as any commercial all-purpose kitchen or bathroom spray. If you buy some lemon or lavender oil and add a few drops, your house won't smell of vinegar.
Before you do your budget each week, put a small amount of money, even if it's £2, aside, somewhere you can't touch it. When you have very little, an emergency fund is crucial. Take this money out FIRST so you don't think of it as a deduction, the idea is to pretend that your income is smaller. It is much easier to save that way, as otherwise you will be trying to save out of "leftover" income which is impossible if there is nothing left over.
This technique works the same way with leftover food. If, BEFORE serving up, you take a portion of food out of your main meal to form the next day's lunch, you are far more likely to get two meals out of it than if you just serve up a meal and then see what is left afterwards for the next day.
Finally, be careful of false economies. Try to plan ahead for when things wear out, so you don't fall into the buy cheap buy twice pitfall. With me, I tried to save money growing my own vegies on my balcony, but after spending money on potting mix, seeds, etc etc etc, I lost my whole crop of EVERYTHING to bugs and aphids. It was heartbreaking. Sometimes it's cheaper to just buy vegetables from Lidl. I have given up on gardening except for bay leaves.
I drink a lot of tea so it saves me a fortune. 
