One of the most important things you can build into these documents is a clause that allows you to perform proper "due diligence" on the property. Basically you want to make sure that you have time to review all of the necessary financial information, management documents, and fully inspect the property itself BEFORE you finalize the purchase of the property. If things are not what they appear to be on the surface, it is better to find out now _ before you own the property than 6 months down the road.
In the early stages there's various options available to you. It is extremely important that you choose the most suitable style so your document presents as professional as possible. You can select from varying styles including Block Style, Modified Block Style, Semiblock Style. You can have a look at these varying options and select the one that you consider is most suitable.