I estimate 8%, and in my own experience with my Hollywood duplex, I'm averaging less than that.Yes, rent control measures have been on the ballot, but they've been consistently defeated, including the split-roll prop affecting Prop 13.I'm sorry you've been brainwashed by the "scalability" argument.

I was originally thinking of aiming for a single family and renting out a room but maybe a duplex or place with 3/4 units is something I should be considering more.

They come out once and measure.  

Now, for all you that dont realize this, When  you look at a house, measure the expansion joints.

I always aim for long term tenants. 

I don't evaluate based on COC return because it's a fairly flawed measurement. 

@Pooshan KapilCap rate isn't a measure of return, but rather one of risk.

Any transfer to an individual, either directly or indirectly, where full consideration (measured in money or money's worth) is not received in return.Does this mean that if I gift my share of the down payment, my name cannot be on the deed of the property?

This increases your repair budget and to keep the repairs proportionate to ARV you have to aim for a higher property price segment. 

Its best to measure twice and cut once.