What should an investor educate themselves about?

Good question!

an investors should primarily know:
-his financial goals & targets
-how the investment system works.
-who are involved in the systems.

then only you can pick:
-the right investment options.
-or, specifically which stocks to invest
-last but not least, when is the right time to buy.

finally, if you what is going on:
-search for tips and tricks how to take advantage.
-look others how they success, and also why they fails.

read
one up on wall street - peter lynch
the intelligent investor - benjamin graham

Risk. You might not always win, but you better not ever lose.

An Investor should decide which investing strategy they are interested in, whether it be stocks, forex, options etc... Then seek out information on your desired investing method, There is an absolute overload of Information out there. The one good thing about the internet, is the information that is available, unfortunately you have to weed through all the junk first. I have read countless books about stocks and options. My main advice to you regarding stocks, is to invest in good profitable companies, that have a long term future. My best reading to do with stocks, was the intelligent investor, one up on wall street, the warren buffet way, and how to pick stocks like warren buffet.
These books all cover the same things, buy good profitable companies,( in which you can understand what the company does to make a living) when they are out of favour with the rest of wall street. and hold them for the long term.

My second piece of advice I have, is to spend time learning how your particular market works, and why it behaves a certain way.

And Finally Do your own research and Invest on your own, because what I am comfortable investing in, you might not be and vice versa.

here is a link to a free ebook that might help answer some of your questions about stocks.
www.sharemarketinvestments.com/covered...

Psychology more than economics. Read "Come into My Trading Room" by Elder. Excellent book for all flavors of investor.

Hi, i recommand you a good and basic tutorial for investing. it covers all Issues related to your Investing and everything around it.

http://www.tutorialforyou.net/investing/

wish it will help you.