That depends 100% on you and there is no one right answer. Just stick to your strategy and risk management (since you are a newbie I am sure you will adjust it after x-amount of losses until you improve your results).

All I can advise is to stick to only one pair since you're a newbie. The EUR/USD is the best pair to trade with because of the affordable spreads. However, it could be boring sometimes because the movement is too slow.

For a beginner, it is not advisable to use more than one pair not unless you can afford to lose all your deposits. I also noticed that most of the newbies who trades with multiple pairs got their money wasted. I don't want to waste your money, so please use one pair at a time.