One way to quickly evaluate a rental property investment is is to calculate the percentage down needed in order to make the property’s monthly mortgage service(including taxes, insurance, and PMI if any) equal to the monthly rental income. The higher the percentage down required, the less interesting the property is as an investment.

The hardest part about this back of the envelope calculation is acquiring the rental market knowledge necessary to accurately estimate the probable rental income for a property. To find this information, check out craigslist.org, grab local papers, or contact local brokers to ask them about similar units that they may have on the market.

I’m a bit torn about IdeaSling.com. The site is trying to record ideas into the public domain with the hope that a motivated individual will love an idea they see and make it happen. The concept is romantic and fun, and it will probably be fairly popular, however, I’m highly skeptical that the core goal of the site will ever be reached in any significant way. Over the years, I’ve learned that ideas are a commodity. It’s easy to come up with an idea, but it’s hard to implement one.

As an example, my current company, Investment Instruments, started with a handful of people in a room for a weekend. Over that one weekend, we generated over a hundred ideas which we felt were worth pursuing. We spent a few months working through them to pick the best, and then finally began implementation, which will continue for several years at least. So, from one weekend generating ideas, to a few months evaluating ideas, to a few years implementing an idea, it’s clear where most of the effort is being expended.

Not to say that there aren’t brilliant, paradigm-shifting ideas out there, but they are few and far between and difficult to identify because of their very nature.

I have a week long series of articles on real estate investing appearing this week on IWillTeachYouToBeRich.com, a personal finance blog by Ramit Sethi. I will also post the articles here starting August 1.

I bootstrapped my first company, which was easy to do, because it was a consulting firm during the boom. Nowadays, it’s harder, but still a very viable, and manytimes advisable, way to go. Here are two blogs worth checking out on the topic:

• It’s a great time to be an entrepreneur by Joe Kraus
• Bootstrap Network Blog by Bijoy Goswami

If you are going the route of raising a small amount of seed financing(<100K) in order build an initial version of your product and gain customers, then you should quickly segment the people you know or meet into two categories: people who like, respect, trust, and share a bond with you and people who don’t.

Most of the people that will fall into the first category will be people that you have known for a while: parents, siblings, college friends, high school friends, etc. A very small number of these people will enter your life after you begin to raise funding, and in most cases, it will take a connection from a friend to begin the relationship and a good amount of time to develop it.

At this first stage of segmentation, don’t worry about who has the financial ability to invest and who doesn’t. That categorization can lead to culling folks who are willing to help you in other ways. Define this core support group first, and if you are having trouble, be generous in adding people who might be on the edges. Once you have this core, nuture it. You will be amazed at how it can grow larger and healthier. Eventually, when you are ready, begin letting your core group know what you are working on. Some will be skeptical, some will be supportive, some will be helpful. Practice your sales pitch on the skeptics, let the supporters give you energy, and take all the help you can get, because you will need it!