Phantom,
Sorry it's taken a while to get back to you. Thanks for the info; it sounds like you arrived at the "I need to learn about investing" conclusion in the correct way.
I'll start out by saying that while I have a degree in finance, I am in no way, shape or form qualified or licensed to give you investing advice.
Right now that's out the way - before you start investing -
- You should have at least a six month float in a liquid savings account (in case you get sick, lose you job, have a "life event")
- You should have no debt (most debt carries an annual interest cost of more than what you will likely earn investing)
- You should maximize any tax-free retirement savings opportunities (most likely you'll be investing this money too, but you need to minimize taxable income before putting money in a taxable trading account. Most companies here in the US offer retirement investment plans for their employees to encourage investing. You should start with an equivalent to those, and pick the maximum percentage you are offered from each paycheck. It forces you to save tax-free.
- You should set measurable goals.
- Outside of tax free retirement accounts, you should save up some disposable capital to start investing with - disposable in this sense not meaning "I can throw this money away" but more "I will suffer minimum adverse financial impact if I were to lose this money".
- You should start with broad-based funds, like Dow Jones or S&P index funds until you feel comfortable you know what your money is buying, and the mechanics of how it buys it.
- You should have a set investing schedule that buys your chosen investments at set times, thereby averaging over long periods.
- Once you feel comfortable with the basic notion of money leaving your pocket and going into a few stock shares or mutual funds that grow, you may expand into areas that you know - if you're in technology, you may buy software shares, if you work in retail, maybe you know the next hot clothing company, if you work in wine, like Gus, you invest in wine.
The idea is to build a piechart over time with lots of balanced slices, that represent broad investment vehicles like shares, bonds, funds, and cash which give you exposure to the economy as a whole.
As for your mortgage, I'm not sure about the effects of overpaying. It depends on your interest rate, what you're paying to principal and interest each month etc. In theory, you should pay down your debt first, but if you're paying 3% on your mortgage, and can make 6% elsewhere for instance, there are times when that may not work exactly the way it appears.
Finally, books.
Barron's Guide to Making Investment Decisions is dated - ten years old - but that is a good thing, because it covers timeless principles while weeding out the day trading fads of the last decade, so you don't pick up any bad habits at the go.