Confirm they are licensed and insured
Start with the basics that protect you legally. Most states and many counties let you look up a contractor's license online to confirm it is active and in their name. Ask for proof of liability insurance and, where relevant, workers' compensation, and confirm the coverage is current.
This step does not tell you if the contractor is good. It tells you they are allowed to work and that you are not exposed if something goes wrong. Do it first because it is quick and it removes the clearest risks.
Read their permit history
This is the step most people skip, and it is the most informative. A contractor's permit record is a public log of the jobs they have actually pulled permits for. It shows the trades they work, the typical project value, the towns they serve, and how recently they have been active.
Look for a pattern that matches your job: several permits in your trade, in or near your town, with at least one recent date. A contractor whose record lines up with your project is a much safer bet than one whose website simply lists your service among many.
Check references and recent work
Ask for two or three recent customers with jobs like yours, and actually call them. Ask what went wrong and how the contractor handled it, since every real job has a hiccup and the answer tells you how they operate under pressure.
If you can, drive by or ask to see a recent completed job. Recent matters more than impressive. A clean job finished last month says more than a showpiece from years ago.
Get it in writing before any money changes hands
Before you pay a deposit, get a written contract that spells out scope, materials, price, payment schedule, and who pulls the permit. The contractor should pull the permit, not you. A contractor who wants you to pull your own permit is often trying to keep the job off their record, which is the opposite of what you want.
No single check is enough on its own. License and insurance cover the legal risk, permit history covers the quality question, and references and a written contract cover the rest.