How much of your portfolio should be in real estate (excluding your primary residence)? Down the road I would like to buy an investment property or two, but would hire a property management company as I have no desire to deal with tenants.
For me, I fund my 401(k) at 10% (which includes employer match), have a good chunk of emergency savings, and then the majority of the rest goes into investment properties. Like I mentioned before, I know I'm not balanced well but we are trying to really build up our real estate portfolio so it works for me in the short term. I don't think there is a good answer to your question and its person specific.
But most, if not all, of your profit is going to be eaten up by your property management fees FYI (unless you are putting 25%+ down).