How to choose a currency pair to trade?

Let's say I want to trade the news and the USA economy recently had news of a booming economy.

Which USD pair should I trade and why?

The Majors are: EUR/USD, GBP/USD, USD/JPY, USD/CHF, AUD/USD and USD/CAD.

How do you select which one is better? What criteria etc?

You have to look at that news and learn to interpret it in terms of the news (general conditions) of the other side of the pair, especially in terms of expectations re. the current and capital accounts for both sides of the pair. There's lots of "gotcha's" in most news items.

In some cases it's relatively easy - for example, recent news on NZD re. business confidence played out quite nicely against JPY because there is already concern about NZD/JPY carry trades, and a sell after such a bad report was nearly automatic.
On a more complex basis, one looks at the recent NFP report from the states - it looks good - lots of new jobs - but one has to look more carefully at things like the the rather dubious nature of BLS numbers, and then at the distribution of those jobs, Was it really positive? My own take was no, but I think I may be in a minority
OTOH, take oil - anything that indicates a higher oil price will usually play out as a short in USD/CAD (since we supply most of the US's foreign oil), but doesn't seem to effect JPY too much, even though Japan has little or no resources. But unlike the US they are both good at negotiating their way around the ME oil patch, and are used to being thrifty w/r to energy. So bad oil numbers tend to favour Japan slightly over the US. So nothing is really cut and dried.
A good place to ask these questions though is over on the News forum, where you will occasionally find people who specialize in an area and can give you specific info.

My sugg. would be USDCAD because they are very close Politically and I forsee 8 - 10 years of growth in particulr provinces which could sustain the current directional move.

This "Current Strength" is what will cause Canada to refrain from increasing interest rates until they are required.

So...
How should You Play It?

In My Opinion, USDCAD has {or, at least is very close to having} reached a plateau and will now be range bound for the forseeable future.
THE perfect opportunity to Buy Low and Sell High.

All you have to do is define the Range.

Do what I do, place all of them on your system. Use same indicators for all pairs. Which ever pair looks like the most promising one to trade, then do it. With several options to choose from, your odds are better to jump in more often.

Good Luck

I follow the same approach: I treat all the pairs under my same T.A. tools. Whichever fits my filters the best, that's the one that goes into my watch list for the day.

Trading news is for the 95 percent of forex traders who fail,(scalpers) trading trendlines is for us 5 percent who do not fail.
Enough said.