If you are new in forex trading, then i suggest you, first practice with demo trading account. Because, demo account is look like a real account. But for practice demo account is the best in forex trading. Actually its not any limit that, you should watch 5 pairs or 6 pairs. Just you need to know the proper knowledge about that pairs, which you want to trade. such as, you have to analysis fundamental, technical site of that pairs.
But, i think for newbie, the best way is, practice with demo account first.