I always buy (cash in) and sell (cash out) via @blocktrades with #Dogecoin :)
https://steemit.com/steempower/@pinay/how-to-buy-steem-power-with-dogecoin

Or, using SBD earnings I buy Steem from Steemit "Currency Market" and Power Up ;)
https://steemit.com/steem/@pinay/buying-steem-and-powering-up

Before Poloniex banned Philippines IP address, I use my Bitcoin from Poloniex to buy Dogecoin and withdraw Dogecoin (use for buying Steem Power) to save from blockchain/transaction fees. :)

I am always on mobile and I have an account with Bittrex but didn't use it because I find it difficult to navigate from mobile.