A trading system is a documented process for selecting, sizing, entering, managing and exiting positions. Clear rules make decisions reviewable; they do not ensure that the strategy makes money.

Specify the Whole Trade

A usable specification identifies the instrument and session, data source, signal, entry order, initial exit, quantity calculation and maximum combined exposure. It also covers partial fills, rejected orders, disconnects and scheduled events.

For example, “buy when RSI is below 30” leaves important questions unanswered. Does the condition need a completed bar? Is the entry at the next bar or a limit price? What happens if the price gaps? Which RSI calculation and timeframe are used? The same indicator can produce different strategies once those decisions are explicit.

Build and Test One Version

Write a versioned rule set before calculating results. A manual checklist can be a system; automation is optional. If discretion is allowed, describe the decision and record when it is used so its effect can be reviewed.

Test the rules on historical data with spreads, fees and plausible execution. Keep a separate period for evaluating the frozen version, and record abandoned variants. A positive result after repeated tuning on the same history may reflect selection rather than a repeatable advantage.

TradingView's strategy documentation illustrates why broker-emulator settings, order timing and nonstandard chart prices matter. A green equity curve does not establish that the modeled fills were available.

Define Risk and Failure Conditions

Calculate size from a chosen risk budget and the instrument's loss per unit at the planned exit. No fixed percentage is safe for every account, and stop fills can exceed the planned loss. Add limits for correlated positions and operational failures.

Define what requires a pause: an unexplained position mismatch, a rejected protective order, an exceeded loss boundary or results outside the assumptions you intended to test. These controls are part of the system, not an afterthought.

Move from Model to Observation

Paper trading checks workflow in real time while keeping simulated and live results separate. A small live account still risks real money. Neither a particular number of weeks nor results within an arbitrary percentage of a backtest certifies a working system.

Review whether discrepancies come from data, fills, rule interpretation or changing market conditions. Make changes in a new version and evaluate them separately. See our backtesting walkthrough for a structured record.

Risk Disclaimer: Trading involves substantial risk of loss. Past performance is not indicative of future results. See our full risk disclaimer.