If you are looking to do a social media campaign, hire a social media company. Within the guidelines of the contract that you draw up with them, you can protect yourself that way. They are used to dealing with sensitive information and it won't be anything new to ask of them and most likely will be standard int their contract.

If you are needing expert advise from someone inside your industry, find some local group (if you are in a bigger city and have access) or find an online community that caters to the industry that you are in. Most likely you will find people there that have already answered a lot of the questions that you might have.

Now if you've done both of those things, take some time and form a relationship with someone in your industry. Then ask them if they would be comfortable being your coach. Write up an agreement and then pay them something so it' a business deal. You can find all kinds of these type of forms online. That way, you're paying them and have a legal backing to say that you were paying for services. By hearing your original idea (a necessity for the transaction) and them giving you advise you'll have a much easier legal standing than just an NDA would have.

Good luck!