1 Sizing by leverage, not stop distance. The dial sets the maximum notional; the stop sets the size that matches your risk budget. Take the second number.
2 Putting the stop below entry. A short is invalidated by a rise — the stop belongs above the entry, and below the liquidation line.
3 Treating positive funding as income. The carry is small next to an adverse move, and the sign flips with the market.
4 Holding a short through a scheduled print at maximum leverage. The liquidation line can sit narrower than a typical overnight gap.
5 Reading a perp short as a share sale. You hold a contract tracking the price, not borrowed stock — no locate, no recall, no dividend liability.
6 Budgeting a total cost without fees. Canborsa charges 0.07% per side, 0.14% round-trip — add it to every cost figure here.