for an apps, i use tabtrader, polo tracker and ztrader although i am familiar with tabtrader only and i using the two other apps for just checking market conditions. i think that three apps is helping me to make buy and sell order in poloniex and bittrex. if you decide to use the apps, make sure you are only setting for trade and not withdraw to safe your bitcoin from the hacking.
That’s a sincere advice though. Never ever use apps to withdraw bitcoins because they are at stake of being hacked. Polo tracker and tabtrader are nice apps to do a safe trading. But just relying on apps is not going to help much. Reading genuine articles by experts really help.