How do I value my trade as equity in a new business?

First sorry for grammar and spelling on mobile.A little background, I am highly experienced in digital marketing and have helped create businesses from the ground up specifically creating all of their branding and software infrastructure level. I own about 3 business I have started; 1) print and digital branding creation 2) website monitoring and system admin 3) digital marketing specifically SEO/SEM.About a month ago I was approached by some friends with a business idea, which isn't something unusual for me. I work with successful and unsuccessful business in my day job I know very well which ones will succeed and fail. I've gotten my fair share of friends that think they are creating the next Facebook and Twitter, so I usually listen for the sake of being respectful then ask them valid questions challenging the idea and most of the time I hear nothing after that.The part that is different is that this is an idea that I actually believe will work. We met and they were asking me what I wanted in equity in return for not only my digital marketing and business experience, but also using my network of contacts that could help with finding investors, manufacturing, and fulfillment. All of which I am willing to put forward to make this a reality. The part that I need help with is how do I value my services? I know that any % of a business that is worth $0 = 0. I would be responsible for all the marketing work; branding, website, package design, marketing (social, SEO, SEM) and that alone could be worth around $5-20k in my time. Also how do I value my connections?I should add, I am planning on being 100% transparent and getting everything in writing before we begin. Lots of contracts and if needed lawyers so we all feel comfortable. We are all on the same page and they are on board with this!Tldr; have a friend with a good idea, they want me on board, I do digital marketing how do I value my trade in equity? see hubwealthy.com/wealthy