There is no hard and fast rule for which coins are best for trading or which aren't. All depends upon present situation and performance of coins. You always need a plan how you should enter and perform in cryptocurrencies market. My suggestion is you should divide your total budget into 3 parts. Parts can be equal in starting and later on divided into different ratios on the basis of performance of first month.
So first part of your budget goes in bitcoin and nothing else.
Second goes to established coins like ETH, XRM, XRP, etc
Third goes to promising and new coins. Third part has most potential to give unexpected profits. All you need to do is reading the market carefully.