I suggest to avoid centralized exchange like kraken or bittrex at all!
It's better if you start using decentralized exchanges which are usually safer, more reliable and above all has no power to block your funds or ask you for further verifications. The downside is that decentralized exchanges are often difficult to use for newbies and have lower volumes. A good choice I suggest you is Waves decentralized exchange, which is fast, safe, cheap and very user-friendly too!