Treat this like a business, with contracts and agreements, exit strategies and percentage of ownership clearly detailed.Especially since this is your first deal.

@Tim Herman Thanks for your insight.I actually have a lender that can do an 80% LTV which would be $240,000 of the $300,000 ARV.What vacancy percentages do you typically do for multi-family/duplexes in the Houston area?

They will be willing to take a certain percentage of that amount. 

It’s an annual percentage rate. 

It could change to any percentage at any point during the lifetime of the loan.

Their ownership percentage could be much much less.

@Jonathan Johnson there are more variables than the basic expenses, so it is difficult to pin an exact percentage. 

What is a reasonable percentage split? 

(I don't even know if this is even an option but the last thing I would rather not do) give a little percentage

Now, new people trying to get into this market are paying 35% (and up to 70% based on the rental rate - some take a higher percentage with each additional day of the month the property rents).