Here's one I prepared earlier (as they say in the classics ;-) ).

10 Questions to ask before you engage a social media manager
 
If you’re considering hiring a social media manager to represent your business online, you need to be sure you’re making a good investment. Before engaging a social media manager for your business, you want to ask:
 
1) What services do you provide and how does your process work? Do you schedule posts or provide them for me to post? Do you manage audience interaction, or do you expect me to do that?
2) What are some of the results you've achieved for your clients? Can you give me links to some of the pages you currently manage? (If they do advertising, ask for ROI data on that too)
3) How do you work with your clients? (How do you get know the business, the target audience, the brand, the ideal customer?)
4) What clients get the best results from you? Why? (ie my clients get the best results when they have a blend of organic and paid strategies because it’s more powerful than just organic.)
5) How often will you be posting? (It's different on each platform, but the minimum viable product on Facebook is 3 times a week if you have less than 10,000 followers. Make sure you’re happy with what you’ll receive for the price)
6) How will you build my business? What strategies do you use? (You're looking for clear strategies that make sense, someone who knows what they're talking about, and can talk about previous/existing clients)
7) How do you communicate with your clients? How often and by what mechanisms (ie Skype, in person etc)
8) How often do you report? (ie I send my clients a short weekly email with a couple of key pieces of data and information on activities undertaken, and I provide a full report monthly in PDF format)
9) How do you communicate what posts are scheduled (ie I give my clients a dashboard they can log into any time and view their scheduled posts, along with previous posts)
10) What do you expect from your clients during this process? (ie What I need from my clients is an understanding of their business goals, their brand, their direction, and any changes in goals and direction. I also ask for images for spontaneous posts, and usually supply a list of suggested photos / videos etc they can provide over time).
 
Every social media manager will do things differently, but you want someone with a clear process and proven track record who can TRUST.

Ask to see previous examples of their work to gauge if they are able to create the type of content you are looking for. Also ask them to create 3 -5 pieces of content for your company and see if they are aligned with your message and they type of content you want to be putting out there. Ask them how much time they think it will take each month to create the amount of content you require. And finally ask how much it will cost - you don't want to be hit with any hidden costs when you receive the invoice. 

"What does a successful social campaign look like to you?"

Too often social media agencies get caught up in vanity metrics and 'virality' and not focusing on the goals and outcomes for your business. SME's need to know their dollars are going towards driving real world outcomes for you, driving sales, foot traffic, bookings and sign ups. 

So before you tell them what you're trying to achieve, ask the above. If they show you posts with thousands of impressions, heaps of Likes and Comments but don't ask what's important to you...

Run.