I was worried too, I've only used blocktrades, then I joined @ionomy. Using this Tutorial on Hive I now just send my STEEM to user name ionomy with code in memo, now you have your STEEM sitting on ionomy exchange.
Next step
From the Market Menu
1: trade STEEM for BTC: I didn't use Limit Order I used Market Order just makes life easier (limit order means you put in the price you are willing to sell/buy, then quantity, then place you order and hope someone fills it). You will get better value this way but you have to wait for someone to trade with you who accepts your price.
2: Intermediate Step: This is my favourite place, I can now buy ION, ETH, HIVE etc, the choice is mine.
3: trade BTC for HIVE: same procedure as 1: sending is easy as well, just send to your HIVE user name and quantity of HIVE tokens. The transactions is not immediate, it may take a day or 2 to appear in your HIVE account.
Fantastic, thanks for the detail!