It involves marketing, salesmanship, learning your re markets so you can calculate accurate ARVs and estimate rehab costs.

@Jody Davis,The next question then would be do you have a repair estimate?

I agree for you to accumulate places makes the most sense to drive up your income and it becomes easier to sell some as new and fun deals come up.

Is anyone here familiar with mill valley and can help estimate an arv?

I've been estimating Taxes as a % of After Repair Value.  

Then hit the internet websites and see if there are any recent sales to estimate current market value.

I have been in my real estate investing career for two and a half years at this point and have accumulated 5 properties consisting of 15 units.

Im estimating 8 ACs and 8 furnaces and install could run about 30k.

Below are some more details with the rough numbers:12 (1 bed/1 bath unitsValue of Land:  ~$150KCost to Build:  ~$500KRent is expected to be $700-$750/unit ($8400-9000 month)Vacancy, management, expenses, CAPEX, etc:  ~$4100/monthNOI:  $4,300 to $4,900Monthly Note ($350K, 20 yr AM, 5%):  $2,309Monthly Profit:  ~ $2,000 to ~2,600Annual Profit:  ~$24K to ~31KValue of property (low end estimate on an 8% CAP:  $645K to $735K)Average CAP rate for new builds in local area is ~6% CAP. 

I'm assuming the buyer would have to include these payments into his or her cost estimate.