make sure you're going through a title company. If you don't you have no idea if the seller can actualy sell to you. Check out htt;://MiTitle.com as they deal with these types of transactions all fo the time. I'd also have an attorney draft the land contract so you don't have problems later by using the incorrect documents, you should try @David Soble of http://www.ProvenResource.com
I've been investing in Metro Detroit since 2003 and have seen many crazy things happen when tryong to do everything yourself to save a few bucks upfront only to lose it all later.
Feel free to reach out anytime.