Warning: I love to teach, so I may get verbose :)

Real Estate works for us, more than paper assets, and less day to day time requirements than building a business for sale (exit plan) or that someone else operates for our profit. Everyone is different, YMMV.

Education is key. If you would hire a coach for exercise/strength training in a gym/fitness club, then I would highly recommend hiring a coach for real estate investment. As I stated elsewhere in comments, we went over the same material (and more) in 6 months with a coach that it took me 3 years to piece together on my own.

Patience - We were not ready to actually purchase our first piece of property until almost 4 years after we started preparing. Preparations for us included making our credit report as beneficial to us as possible, learning about the responsibilities of being a landlord, learning about the job duties of a property manage (even though we sub that out, we still want to know what is appropriate and what is not), learning about negotiations (did you know you can include almost anything in a buy/sell contract? "We'll pay $x and this 320i BMW in return for that piece of property" is a deal I heard referred to by another real estate investment expert), learning about the legalities of business entities with respect to real estate ownership, and so on. Now we just save up for the next down payment, then start looking for the next deal. And although there are ways to get into deals without a large (or any) down payment, they usually require considerably more effort and time, and I have a service business to keep going. So we do it the more lazy/easy way, with cash and financing.

Due diligence - It is better to walk away from a deal that I just can't make cash flow enough, than to get stuck with a poor/sub-performing investment. We walked away from quite a few deals, even though there were several I was relatively sure I could make work. On-site inspections have uncovered many potential gotchas that would have been financially painful. Some landlords extract the most profit out of an investment they can, and this can frequently result in much deferred maintenance, which can get very expensive very quickly. And like a start-up, you can only sustain a given burn rate for so long, before the deal crashes.

Teamwork - Although I have been gifted with what intelligence I have, it is not a good thing if I am the smartest person on my team/in the room. We all have different strengths, and I am not good at everything, so I try to surround myself with teammates that provide those missing/weak areas I have, as well as mentors who have already gone down that road. Having a good property manager go over a property will help me identify concerns, see places for improvement, etc. Having a reliable contractor (I am still looking for my next one, last one wasn't a good fit for us) can keep me out of those large up-front costs. A knowledgeable attorney for real estate investment in the area I am investing in is very important - It would be terrible to build up a portfolio then lose it all because I did not adequately protect ourselves (entity + insurance + operating practices).

Okay, enough. Sorry for the deluge, but I really _like_ the process of real estate investing.