I had no choice but to cut my monthly expenses as far as possible after my divorce. I'm down to one income and have huge debt.
Here's some things I did to keep afloat.

I rang all my service providers (gas, electric, phone) and negotiated with competitor companies for lower prices for same service.

I re-negotiated my mortgage with the same bank. I shopped with opposition banks and companies and took those quotes to my bank. They matched the rates just to keep a customer so I didn't have to refinance. Saved fees and dropped my payments.

I grow my own vegetables in pots under the patio - tomatoes, spinach, zuchini, beans, lettuce, parsley, garlic, eggplant - whatever is in season. It saves a fortune off the grocery bill.

I downloaded hundreds of cheap recipes from the net to help feed me and my daughter on the smallest budget possible.

I cut the cable channels the moment he left. That was an easy decision.

I make my lunches for work - it saves me a huge amount from bought lunches.

I make my own house-hold cleaning agents from natural products (downloaded from the net). Environmentally friendly, they clean better and they cost 1/4 the price of store-bought cleaners.

I make my own dog food. It's better for the dog and so much cheaper!

I car-pool to work - i only drive every second week now. Lower fuel bill.

There are hundreds more things I could be doing, but these are the things that come to mind