One, only one

I admire people who open twenty or more trading positions. If everything goes well, they can potentially make a great profit. If not, well then not... 
The basic rules for long living and profitable trading are simple: 

• Do not risk too much per trade (less than 2% of your money)
• Do not trade too many different currencies, indices, stocks etc. - at least not in the beginning of your trading career.

If you trade only one currency pair e.g. EUR/USD sooner or later you'll get very familiar with the dynimics of that currency pair and will be able to understand what has e.g. a periodical effect on it. You'll know the volatility range on a ordinary day. You will be able as well to better predict what will happen to your currency pair when a war breaks out, economical crises occur (global news) etc.


It is like in real life. If you know something well, you'll know how to master it, will be able to get the most out of it and will  more likely be able to rely on your intuition when this is necessary.  
It is understood that with one currency pair the trading opportunities will be limited, but it is not necessarily a disadvantage. 
So, focus on something and do not waste your energy trying to master many other things at the same time! Better having one happy wife, than five instable funny relationships.