What am I missing? - Rental property in Raleigh

[Luis Suarez]

I found a property that I am interested in purchasing as my first rental property.  It's not an amazing deal, but the numbers seem to work.  Can someone double check behind me?

ARV: $68,0080

Purchase Price: $40,000

25% Down payment: $10,000

8% interest (could be a little higher or lower) @ 30 years

Estimated Repairs: $3000

Points: 525 (Unsure about this one)

Monthly Income: $680 (based on history, this could be more)

Monthly expenses: $634 (10% vacancy, $120 HOA, $20 Insurance, $61.20 repairs)

I would plan to refinance, and cash out in 12 months..  

I'm being very conservative when calculating the expected revenue, and i'm trying to over estimate the expenses just to be on the safe side... What are your thoughts? Should I provide more information?