British Gas
All the normal advice for energy suppliers applies to British Gas. Submit a meter reading at least monthly. If your Smart Meter isn't already sending readings at least once a month (ideally daily to cover price-change days), submit a reading just after prices change, every three months. Many Smart Meters don't communicate, so check. You can turn on more frequent readings being submitted in your BG Energy account. This is particularly important with BG, as they issue statements only every six months for Direct Debit customers, or longer if meters aren't working well. It is still quarterly for those who pay when they get the bill. Please ensure payments cover usage over a year to avoid going into debt. You can make one-off payments and also change your direct debit level.
If you are not a domestic customer, such as industrial or commercial, and that includes landlord's supplies and often holiday lets, you are not subject to Ofgem's domestic energy cap. Still, a scheme can reduce costs during price spikes, but you need to make sure your tariff includes it. Businesses often use brokers to shop around for the cheapest, often three-year, fixed tariffs. Business-deemed tariffs can be extremely high and can be over a pound (£) per kiloWatt.hour (kW.h), based on an example I have seen.