Acting as a middle man for the first time

[Oriol Serra]

I didn't know which forum was best to post this, so I'm posting it here.

I am Spanish, and I switch between the city of Barcelona and London pretty frequently. Recently, I found that there is a lot of property offer in Barcelona, and the Balearic Islands, but not enough demand to cover everything. I also realised that British people like to come to Spain to spend their holidays, and some of them even buy houses here (mostly in Ibiza, Mallorca, etc.) I also checked of course that nobody is doing it right now in a big scale, so there is space for small middle man to work.

I am though a little bit lost here. How should I proceed? It's obvious that I need to act as a middlemen between London buyers and people selling houses in Spain, but I can't ask for the money myself, since I do not own any property. I thought of making the sellers some sort of contract that stipulates that I will get a commission in case of getting buyers. Just by knowing how you guys do it in the US would be a good help, since I could start learning more from there.

Thanks in advance.