i found a good site which you can practice and learn on trading. you can visit on bitmex.com. you register first in bitmex then you can visit on here testnet.bitmex.com then you can start to trading. but unfortunately i am not trying this because i think you need to practice with real balance and you don't need to have big balance to start. you can start deposit $10 to buy bitcoin and then send the bitcoin you bought to poloniex or bittrex and you are ready to practice trading. but before you decide to buy one coins, you need to search and analyze the coins maybe you visit in coinmarketcap.com to see the list of the coins and only choose top twenty which you think you can make your first profit. good luck.