Ask HN: Template for initial contract between two co-founders?

Hello everybody. A friend of mine and myself are thinking of starting up a little side project. If this turns out to be successful, we'd like to have a contract in place that assures stuff like we get 50-50, important decisions must be taken by both of us etc. in general have an initial contract set up between the two of us.

Has anyone had experience with this and can you give some advice? Are there some online templates/samples of contracts like this?

Thanks!