Forex is a trading instrument and not an investment where you speculate how the price will move in the near future. If you are asking about the right pairs then any major pair will do. In the beginning you can stick to EUR/USD, then after some experience can add other pairs to your portfolio. But stay away from exotic pairs at least as a beginner.
Forex for beginners you should stay with major currencies pairs like EUR/USD or USD/JPY as they have high liquidity and not too risky volatility.
Major pairs like EURUSD or GBPUSD have good liquidity for trade and they have less spreads as compared to the exotic trading pairs in my opinion.
Exotic pairs are the most dangerous trading instrument, there are some drawbacks on exotic pairs, the high spread is a common issue when trading on exotic pairs, trading on gold or silver also challenges trading pairs.
Forex can be profitable if the trader has good trading skills and emotional stability and is careful about minor details while trading.
Again all of these above mentioned requirements does not comes right over the night we have to spend time with it.
Forex is for traders who can adapt to the changing market conditions. It’s for the brave heart who knows that the market makes sudden moves but still trades on the basis of past market analysis. It requires experience and skills to make the most of your forex career.
The only thing a trader should adopt should be focus, discipline and patience primarily while learning in order to become successful as per my own personal opinion.
Forex is a long-term gain and definitely a get-rich-quick scheme. A new trader should focus on getting proper education on trading and understand all the basic concepts first, aiming for profit as this stage isn't exactly necessary. However, i would still suggest they open a micro/cent account instead of the demo as even trading with a small amount of money will teach them better trading discipline and overcome their anxiety.