To be able to take short positions, we need to understand margin trading. Trading on margin means we are trading with borrowed money. On exchanges like Poloniex, we can trade Bitcoin with a handful of coins (there are fewer coins offered for margin trading) with 2.5x leverage. That is, if we own 1 BTC, we can borrow up to 2.5 BTC to trade with. To be clear, this is not 2.5 BTC that we own. Now, on a trade that nets us 10% profit, we are bringing home .25 BTC instead of .1 BTC.
Use small buy-ins, and don’t margin trade or short unless you know your stuff. The smaller your bet is compared to your total investable funds, the less risk you are taking on every bet (one of many insanely important things we are covering here). Putting it all on black is tempting, but then if it comes up red, you have nothing left to invest. Live to fight another day by learning to manage your buy-in size. As a rule of thumb invest 1% or less per buy-in (yes, that small, really; losing 100% of 1% leaves you with 99%, losing 1% of 100% leaves you with 99%. Small bids offer the same bet, but with way less risk). Put reward aside and practice risk management and capital preservation until you are very experienced (and thus, by logical extension: don’t margin trade or short unless you know what you are doing, as those leveraged bets magnify your risk by their very nature). See Kelly criterion.
No, the successful trader is not me. I’ve gotten lucky a few times and I’m still refining and trying out strategies; on the other hand, I’m part of communities of people who trade on a daily basis to grow their portfolios, and while some of the results can be attributed to luck, a majority of it is based on fundamentals, good habits, and experience.