I am a software developer and for the past 4-5 years I've worked part-time on an application related to fantasy sports. I enjoy toying with the marketing side of things but I focus mainly on writing code and improving the functionality of the application. My application is completely free but I do make money off advertisements and affiliate sales. The idea is down the line I will charge a small fee for 'premium features', but that a free version will always be available.

I was recently contacted by someone who is a sales/marketing specialist and they are proposing to form a partnership where they would promote/market the site and I would focus on the coding side. This person has offered to use his own money to finance the marketing of the website in exchange for a partial ownership of the company. I've never considered a partner so I'm in uncharted waters here.

Because I've already put in 4-5 years of sweat-equity into this business it would be very difficult for me to give up any ownership in the short-term. I could definitely use the help promoting the site, and would be more than willing to pay this person for their efforts, but I'm not sure what would constitute a fair deal at this point.

My traffic/income has grown steadily over the years without much marketing; last year the numbers jumped by around 300%. We're not talking big-bucks here, but I have total belief that with the right promotion and approach the sky is the limit. For the longest time this has just been a hobby site for me, but the new guy believes it has much higher potential.

Some of my out-standing questions are:

1. Should considering a partnership even be an option at this point? I believe it is way too early to even think about since I barely know this person, but even if trust was built how would they ever make up for my 5 years of sweat-equity? I don't know how you quantify that.

2. If I choose to simply pay this guy a percentage of the profits for his promotional/marketing work, what is a fair number? If I theoretically made $2000 last year, would I only pay him a percentage of the profits over and above $2000 (the logic being that $2000 is the floor since this was made the previous year)?

3. In regards to splitting up the profits, would 50/50 split be the only fair spit? Would there ever be trust that we both put-in the same hours? I'm not even sure that this is possible.

Has anyone else ever been in this situation? I'd love to have some feedback and maybe some lessons learned so that I go down the right path.