What changes inside.
For a suitable lock, the internal key combination is changed so a different key works. The old key should no longer operate that lock. This is different from cutting another copy of the existing key.
Condition comes first.
A worn cylinder or a bolt that doesn't line up with the frame may need attention as well. Rekeying doesn't repair every fault. Show which locks work smoothly and which ones have become awkward.
One key may be possible.
Compatible cylinders can sometimes be set up to share a key. Mixed key systems, specialty locks or unsuitable hardware can prevent that. Include the security door and door from the garage in the discussion if you use them regularly.
Finish with a simple check.
Test each changed lock from both sides where appropriate. Confirm that the new key works smoothly and the old key no longer opens the changed cylinder. Decide who gets a copy and where a spare will be kept.
Review the keys passed on by the previous household.
Decide which doors that key could open.
Check authorization and the doors involved.