What moves your credit score
These are FICO's general scoring categories. Their importance can differ for an individual file, and other scoring models use different approaches.

Payment history
~35%Past repayment is the largest of FICO's general factor categories. Autopay can help, but check available funds and confirm each payment posts. Reported missed payments can harm a score; the effect depends on the rest of the file.
Amounts owed
~30%This includes balances, how many accounts have balances and revolving utilization: the amount reported relative to available limits. Lower reported utilization can help, but 30% is not a universal safe cutoff and no payment amount guarantees points.
Length of credit history
~15%Models consider the age of accounts and other history. Closing a card can reduce available credit and raise utilization; a closed account can still remain on a report. Weigh fees and overspending risk before keeping an unwanted card only for its age.
Credit mix
~10%Managing different kinds of credit — a card, an auto loan, a mortgage — shows lenders versatility. Don't take on debt just for the mix, but a natural blend over time is a small plus.
New credit & inquiries
~10%Each application can add a hard inquiry and lower your average account age. A few over time is fine; many in a short window can look risky. Rate-shopping for one loan in a short window is usually treated as a single inquiry.
Source: FICO's scoring-factor explanation. The practice simulator uses illustrative point changes, not the FICO model or your credit report.