That is a pretty open ended question and depends a lot on your goals.

I'm a part-time real estate investor in the Detroit area who is looking to get into multifamily investing (10-20 units), with the goal of making my first purchase this year. 

It just depends on your goals and how much you have to work with.  

My 5 year goal is to make enough in passive income to quit my job in order to spend more time with my two kids, travel more, and secure retirement. 

Assuming your market is out of wack with that pricing, which CA always is, you do not invest.Owners of rent controlled properties are in a very difficult situation, as you will also be in if you buy, so your goal is to take advantage of that fact.

Which leads me to my goals in REI - the end goal is to build a rental portfolio that will provide enough income to allow me to quit my job, but I'm not in a place financially just yet to start that.

My current personal goal is to get my family together again as soon as possible.

Or, I look at the overall robust economy, the relatively strong housing market, and wonder if I'm entering at a bad time - but then realize that when/if things crash, that'll be another round of changes that provides for opportunity.Opportunity is born from change, and at 42, I'm old enough to know that the secret to doing something is to just get started, and to keep chipping away at it.Anyway, my short term goal, once I have finished doing enough research and working on getting the overall engine in place, is to get a couple deals under my belt, and get an idea of what pieces of my process needs refinement in order to scale up a bit.

If you want a specific CoC return @Justin Fox gave you an easy way to set a CF goal.If it were me, I'd figure out my goal and throw the relevant data (rate, appraised value, LTV, Op Data ect) into excel and have a data table show me what my CF looked like under different circumstances (ie. varying combinations of LTV and desired return) Then, assuming I had its modeled out, I'd do the same for IRR. 

As my wife and I explore real estate investing and try to put our passions into action, I sometimes feel discouraged and as though there is a large veil between me and my goals that I just can't break through...