I personally have a lot more trouble with the mid term calls than with the short term predictions. Identifying a likely developing trend, and selling or buying into it seems relatively easy for me. But the question how to take your profits, in USD or BTC, *that's* the tricky bit, imo. Park them in BTC, and you'll see your profits melt away. Park them in USD, and one swing you missed later, and you only buy 2/3 of your original coins back.