You also need to show them something along the lines of results. I have found that if you've done even something small, doing a nice writeup in powerpoint showing how you got into the deal, what you did, the returns you made, etc...show that you might be able to generate these returns for your potential investors.
Then you just need to put it out to your network. You would be amazed the appetite out there to find a reasonably safe investment with someone who they know, that pays them at least 8% (which is the usual preferred rate these days for investors to ask for). There's no one place to go to, nor is there a quick way to do this, but it is very doable. We just started a fund and were looking to raise $2 million. We ended up cutting it off at $4 million and turning down money so we could get started.
The key there was to have a track record that we were able to professionally write up - I had about 9 years experience running smaller properties from 4-24 units - and the investors felt this experience would translate to bigger properties. Second - get a good team - legal, accounting, and property management (even if they're friends who you cut in for a couple of points). If you are getting investors, you'd want to have the agreements and all put together up front so if someone says, "Oh, why don't you send me your information", you can 5 minutes later send him your PDF/Powerpoint of your background/track record, your proposed deal structure (either a basic document on up to a Private Placement Memorandum), and a very detailed pro-forma of your proposed deal, showing the annual projected cash flows out 7-10 years, then showing an estimated sale in the final year. This way, the investors feel like "this guy's on top of it" and you'd be surprised at the positive reactions you'll receive once you start putting it out there.
Some of the bigger investors i know who invest large family funds and the like all are saying "there's a lot more money out there than there are good deals". So good luck - and go find some of it!