Choosing an SEO agency seems like a bit of a leap of faith, since it takes time for your rankings to improve. There’s no way to take it for a test drive, so you have to trust the team ahead of the data Local SEO.

Begin with their own website Do they rank for anything relevant? Why would you trust an agency with your domain when they can’t even rank for theirs? Run a search for their name combined with a service term and see where they rank.
Request case studies but read them carefully. ‘Traffic up 300%’ is meaningless without context. From where?
For which set of keywords?
Did leads increase? Real case studies will specify the starting point, time period, and the result for the business.
Get to know the person who’ll be doing the work. Many agencies cut a great first impression with a clever sales pitch and then hand you off to a novice once you sign the contract. Find out who will be doing the day-to-day work for you and how much you’ll be in touch.
See how they clarify. A good agency should be able to articulate its approach in straightforward language. If every answer is cloaked in jargon, that’s generally a means of avoiding commitment.
Be wary of contract lock-ins. 12 month deals that cannot be exited are a red flag. Good agencies will provide a short initial term or monthly rolling contract after a trial period.
And finally, ask what they won’t do. An honest agency won’t engage in paid link networks or keyword stuffing. If they agree to anything, they’re probably guessing.
Don’t rush. Ask three or four agencies the same questions as you would each other and select the one that appears to have a real interest in your business rather than just interested in closing.