How to determine what is a good deal?

When you analyze a real estate investment, there are many factors to consider:

The current market value of the home.
The potential market value, such as how much is the area in demand and home prices appreciating. What is a reasonable increase in value?
The rental value of the home, how much rent will the current market pay for this home?
What are the taxes and insurance cost? What are the HOA fees?
When you rent the property, what is the amount paid in principle each year? This is actually income to you as the tenant rent is covering the mortgage payment and thereby increasing your equity in the property.
What is the expected tax write off for the property? For example: The value of the home, excluding the value of the land is a depreciating asset. This is determined by your own income tax rate.
What is the property management fee? I do always recommend you use a professional property manager, it is very easy for owners to be stressed in dealing with tenants. I have not found it to be a stressor, but then again I've owned and managed a real estate agency for 20 years:-) It's not a job for everyone and having a manager will give you freedom from any duties and responsibilities to manage the property.
Now when you calculate the money you invested, such as your down payment, closing costs, repair costs, etc and add in the rent to be collected, equity increase, tax benefit and minus other expenses like Property Management fees, Taxes, Insurance, etc....you will arrive at the ROI of your investment property.