Rule 1 — Full balance, every month
If you cannot pay the full statement balance by the due date, treat the card like a debit card with a hard stop — interest erases most reward maths.
Rule 2 — One primary card
Until your system is boring, avoid optimising across five products. One card, one autopay from a current account with a buffer.
Reader story
“I used BNPL for trainers and a card for nights out — the overlap meant I never felt ‘in debt’ until both hit the same week. Pausing BNPL and calendar-blocking statement dates fixed 80% of the stress.” — Priya, 26, Manchester
Rule 3 — Credit utilisation
High utilisation can weigh on scores even if you pay in full. If you need a score-sensitive month, pay mid-cycle or request a sensible limit review — not a shopping licence.