To add to his sound reasoning based on population sizes, we must consider the percentage of persons who read but don't act (or don't act much).

I was planning on buying a duplex with a partner that was going to help out with the down payment, and in return he would get a percentage of profit.

Fee only planners will consult for a fee, and charge a percentage of your portfolio rather than commission on a purchase. 

The finished, meaning subdivided and approved lot value is typically valued as a percentage of the finished product value.

Development investing in my opinion is the best way to go only for the fact that the percentage on the return rates are so high, I do not see myself investing in anything else. 

@Jeremy CollinsWhen buying commercial, many times the bank is looking at the property more closely then they are looking at you, so depending on the transaction, they may not care about your credit.However, other common forms of financing are: seller financing (good to have in commercial), private funds (investors with money invest in the property for a percentage, terms change depending on where funds come from), partnerships (get people to go into the deal with you), short term bridge loans (also called hardmoney), and there are some more creative ones as well.Good luck!

That is because of the amount of effort yo have to put into getting one and the percentage of actual successful purchases won't support the building of a business using them as a primary method.

Despite all the hand wringing you see on the forums about how Houston is going down because of oil prices, fact remains oil is a diversified industry now and doesn't comprise as large a percentage of the economy as it used to.

Most builders are cost plus meaning they tack on a percentage based on the cost of materials.  

On the ones we put skin in the game, its a percentage of how much we are putting in, then the assignment is recorded in that percentage.