A 100-point jump in six months is realistic if the thing holding you back is fixable fast — high card balances or a recent slip. Here are the levers that move quickest. Educational only.
Credit utilization (balances ÷ limits) is about 30% of your score and moves fastest. Getting under 30% helps; under 10% helps more. Paying cards down before the statement closes is the single biggest fast mover.
Payment history is ~35% of your score — the largest factor. One 30-day late can drop a good score sharply. Autopay at least the minimum on everything so a slip never happens.
Pull your reports and dispute genuine errors — wrong balances, accounts that aren't yours, a paid collection still showing owed. Corrections can post within a cycle or two and lift your score with no other effort.
Don't close old cards (it shortens history and cuts total limit, raising utilization), and avoid a burst of new-credit applications. Length of history only grows with time — focus your six months on the levers that actually move fast.