1. Start with executable observations
The two latest observed trade sides describe transactions that recently occurred; they are not a complete order book. Compare them with completed five-minute or hourly averages and check the timestamp. If one side is missing or stale, wait instead of inventing a price.
2. Estimate the margin after tax
Subtract the purchase price, Grand Exchange tax and a slippage allowance from the intended sale price. A large visible spread can disappear after tax or move before either offer fills.
3. Check two-sided volume
Volume on only one side does not demonstrate that you can complete both legs. Use the slower observed side, take only a small participation fraction, and reduce the first order to a probe while learning the item.
4. Respect buy limits and free capital
An attractive item can still be unsuitable when its buy limit is unknown, the required quantity exceeds recent flow, or it ties up too much of your bankroll. Diversification cannot remove market risk, but it can prevent one stalled offer from occupying the whole treasury.
5. Record actual fills
Replace estimates with your real purchase and sale prices. Include partial fills and tax. Review realised results rather than judging a method from the most memorable win.
When Fira recommends waiting
No recommendation is a valid outcome. The trading desk pauses candidates when quotes or volume are stale, calculated profit does not survive tax and buffer, prices are moving unusually quickly, or your settings leave no sensible quantity.
Flipping can lose money. Roald & Sons provides calculations and decision support—not guaranteed profit, automated trading or access to your RuneScape account.