Indices are fun to trade because they have volatility, and the swings can be big. That also means they can be dangerous and expensive if you don't know what you are doing and let a position go against you.
You will learn from your mistakes, and assume that you will need to make the same mistake quite a few times before you learn the lesson.
You can get a lot of practice by using spreadbets, and experience the emotion of trading. Trading is probably 90% emotion, and the only way of knowing your demons is to trade. So get yourself an account with, say, Financial Spreads who allow you to trade pennies per point on the Dow. This is important, because you are statistically likely to lose the lot. Companies such as Cantors have a minimum bet on Dow of £2 a point (correct me if I am wrong), so you won't get too many trades in before you lose your pot.
As an example, the Dow can swing 400 points in a day. So if you are trading EOD (end of day) then you need to have sufficient depth of stops in place. Remember too that Financial Spreads only let you use stops if you are betting a minimum of £1 per point. If you are trading 1p a point, you do not need to use stops as you should be able to lose £4 without worrying too much. £400 is a different matter entirely (unless you have pockets down to your toes).
And do pay attention to ChartMan's daily review of the Dow which he posts each evening - you will learn from these, and every day is different (although the same patterns do keep appearing).
Don't even consider giving up the day job until you are consistently profitable under all conditions - in two years you might be in a position to consider it!
Do feel free to ask any further questions, and we shall try and help.