Sizing the lot
The simple formula: lot size = risk amount ÷ (stop distance × value of a move per standard lot).
Gold example: balance $2,000, risk 1% = $20. Entry 4,000 and stop 3,980, a $20 distance. Per standard lot each dollar is $100, so the distance is $2,000 per lot. Lot size = 20 ÷ 2,000 = 0.01 lots.
EUR example: risk $20, stop 25 pips, each pip = $10 per standard lot. Lot size = 20 ÷ (25 × 10) = 0.08 lots.
If the size comes out below 0.01, the stop is too wide for your balance: lower the risk or wait for a better setup.