Let's take a look at this very simple forex trading strategy based on the crossover of fast moving averages. Here's how you do it.

On what currency pairs can I trade this strategy on: Any pair you wish.
What time frame should I use: 1 hour (H1) or 15 minute (M15) chart.
What indicators do I need: 10 EMA, 25 EMA, 50 EMA (Exponential Moving Average)

Entry rules:

You want to watch for the 10 EMA to cross the 25 EMA. When this happens, you'll need to be prepared. When the 24 EMA crosses the 50 EMA, you will either buy or sell, depending on which direction the EMAs are crossing. If it's crossing up, you buy. If it's crossing down, you sell. You might want to wait for the bar to close before placing the trade to make sure that this is a valid signal and not a false alarm. This way, you'll filter out some of the fake crosses.

Exit rules:

First option: Close your trade when the 10 EMA crosses the 25 EMA again.
Second option: Or you can exit your trade when th 10 EMA comes back to touch the 50 EMA. Perhaps you'll want to wait for the close of the bar to confirm that the 10 EMA has indeed crossed to the opposite of the 50 EMA.

Advantage:

This is a very straightforward strategy. Works well in trending markets, or during a big price breakouts. It is good for high volatility situations.

Disadvantage:

Fast moving average indicator reflects current situation of the market, rather than predict future movements as it is a follow-up indicator, or also called a lagging indicator.

It can cross and uncross many times, which is why it is unwise to use this strategy in sideways market. You also need to watch it all the time, although some broker platform (e.g. Dealbook from GFT) has indicator alarms which will ring when the lines cross.