Social Media Project-How Much Should I Charge

I got connected through a friend to a company manager who wants me to manage their Linkedin profile as a trial project. They are not even sure what they want me to do and they have no metrics set. After researching the company it seems like my task is to start from scratch! I want to make a decent company profile, increase the number of follower and community engagement. Other than this outline, I don't really have more planned for the campaign. I do not have much experience with Linkedin but I know that building a profile with followers and active groups there is a challenge.
I wanted to ask people who have done this before, how much would you ask to run the campaign? I know the way to show improvement is to increase the number of company followers, which is not an easy task. How much time Should I promise before showing results? what metrics should I promise?

Thanks for your input. I hope I posted this question in the right section.

Just try to get about twice or more of what it costs you just to make sure you reap a profit. That always worked out for me.

That's a good point to start with. Anyone cares to elaborate more?