the reason why es vs ym is good for a beginner is it gives you a micro es. Most beginners underestimate how much capital it takes to trade just 1 es. So, they daytrade with tight stops until all their money is gone.
with the spread you can hold overnight and see what it would be like to be a big trader with lot's of money.
as far as making money, it is difficult, unless you have an idea about a particular dow 30 stock. Mean reversion is dangerous, especially if you start averaging down (although with the spread it is an option.)
but like I said, after you hold a day or two (or even weeks) and survive a big move, you will probably give up the idea of trading 1 es and being forced to get flat on the close regardless of what the market did that particular day.