You will need to gather assumptions or facts on property management fees (10% typical average), vacancy rate, down payment or skin in the game (typically 20% for conventional bank mortgages or 25% hard money lenders), purchase costs ( could be more or less than asking price), rehab costs/expenses( estimated costs of repairs in your area on common repairs/ fix up costs to make Rental habitability, security, safety within or above state and local landlord/ tenant laws/codes).

@Kenneth Garrett that is a very rare and favorable situation you have to not put any money in or have any "skin in the game" per say.  

If you we're looking at a 20 space park that would be seen as less of a "risk".2) Skin in the game.

Split everything 50/50 and put just as much skin in the game as him.  

You will need to put money into the deal, they will call it "skin in the game". 

They often hold the note themselves so they'll want to ensure you pencil out, the property pencils out, and that you have skin in the game.

I know it is always somewhat of a gamble, but you have to get some skin in the game.

A prudent seller will often require some down payment to ensure the buyer has some skin in the game.

If you had a lot more money/skin in the game you would stand a better chance.....  

In theory this is correct.. but in CA ( and all states are different) it could take you 6 months to evict them so that's six months of payments your making.. the could leave you a 5k mess ( pretty common in a eviction scenario).. and usually when folks starting out do this with limited capital when they make money on these deals they DONT save it they will spend it  LOL.. this is partly what crashed the market last decade.. investor with little to no skin in the game and no where near enough capital reserves.. any business with out proper reserves is destine to failure.