Payment history and credit utilisation together account for most of your score. Everything else is secondary, so fix those two first and ignore the noise.
**The factors, weighted roughly:**
1. **Payment history (~35%)** — do you pay on time? A single payment 30+ days late does substantial damage and stays on your report for years. This is the most important factor by a distance.
2. **Credit utilisation (~30%)** — what percentage of your available credit are you using? Keeping it below 30% is the standard advice; below 10% is better. This is the fastest lever, because it updates monthly.
3. **Length of credit history (~15%)** — older accounts help. This is why closing your oldest card is usually a mistake.
4. **Credit mix (~10%)** — a combination of revolving credit (cards) and instalment loans looks slightly better than one type.
5. **New credit enquiries (~10%)** — several hard enquiries in a short period lower it temporarily.
**The fastest actions, in order:**
- **Set up autopay for at least the minimum on every account.** This eliminates the single most damaging event. Do it today.
- **Pay down card balances**, or pay mid-cycle. A useful trick: your statement balance is what typically gets reported, so paying part of it before the statement date lowers reported utilisation even if you're paying in full anyway.
- **Request a credit limit increase** on an existing card. If your spending stays the same, utilisation drops immediately. Check whether your issuer does this with a soft enquiry.
- **Don't close old cards.** Closing reduces available credit (raising utilisation) and eventually shortens your history. Keep them open with a small recurring charge to stay active.
- **Check your report for errors.** A meaningful share of reports contain mistakes — accounts that aren't yours, wrongly reported late payments, closed accounts shown as open. Disputing an error is the single fastest possible improvement.
**What doesn't work**: 'credit repair' services promising to remove accurate negative information (they can't), closing accounts to look tidier, or carrying a balance to 'build credit' — that's a myth that costs you interest for no benefit. Pay in full every month; utilisation is measured at statement time, not by whether you carried debt.