We get an additional deal or so per month from our SEO, our network of other investors, wholesalers and agents. 

Wholesalers, yellow letters, bandit signs, guerrilla marketing, website with seo/blogs, vehicle signage, shirts, bumper stickers, business cards, door knocking, networking, realtors, TV, radio, and other things I'm forgetting.I agree with Mathew that contracting also scales and supplements your business.

I effortlessly self-manage 17 doors in SJ, mostly single units with a couple of duplexes.

Has anyone ever used Elance or Odesk to find someone to do SEO and content writing for your website?

They'll identify what you qualify for and get the deal done effortlessly 

You're mind will automatically act on that input and start to help you to effortlessly take the actions needed to make you millions while simultaneously attracting million dollar opportunities into your reality.

Granted I didn't become an seo master or anything, but I received zero leads.  

This also gives you the ability to have a professional looking e-mail rather than some google or yahoo address.Of course, if you want a REAL web presence where people find you rather than you finding them (business cards, etc), then you are in the realm of SEO and need a real developer and spend real money.

Unless you are going to dominate SEO and have your rental's website appear on the top of Google searches, your best bet is to use one of the above sites. 

They are all doing SEO wrong.