I need advice on marketing an Investment Opportunity.

I have been granted the opportunity of earning a small but much welcomed commission for giving referrals of interested investors to a developer.

I need advice on marketing using email, have own website, news paper adverts, online adverts.
I need advice on the marketing laws as I’m giving referrals and not marketing for the company it self.

See the basic concept of what the investment is below.
-Invest directly in a development of townhouses and a retirement village.
-Earn very good returns.
-Capital will be guaranteed.
-Dividends can be paid quarterly.
-All capital and returns will be held and managed in attorneys trust.
-Only limited opportunities still available

1. What is the least information that should be in a news paper add to be effective?
2. What information should be on a website add like gumtree to be effective?
3. How should I structure a first introduction email to be sent to a potential interested party?
4. I would also like to know what information I may place on my website but I do not want to give too much information away as my goal is to be the middle man.

What would investors look at and how can I do this professional, legally and free if it is even possible?

I can obtain all information surrounding the investment etc.

Thanks for your input guys!