Start with the bill, not the advert
Collect a recent bill or account screen for broadband, mobile, energy and insurance. Note the current price, contract or renewal date, usage and any extras. That gives you something concrete to compare.
Use less
For metered services, look for waste that can be removed without compromising health, safety or normal life. Energy use, unused mobile data and paid extras are different problems, so tackle them separately.
Pay less
When a contract or renewal allows, compare like with like. Check exit fees, setup charges, annual price rises, cover levels and service quality—not just the headline monthly price.