Your position size should come from...

Your stop distance and risk rule

Why risk only a small % per trade?

So a losing streak can't wipe you out

Two traders take the same trade. When it fails, one loses 1% of her account and the other loses 30%. The difference isn't the chart. It's position size.
Position size is how much you put into one trade. Many professionals risk only 1–2% of their account on any single idea.
With US$10,000 in your account and a 1% rule, one losing trade should cost you at most US$100.
Work backwards from your stop loss. If your stop is 5% below your entry, a US$2,000 position loses US$100 when the stop is hit (5% of 2,000).
The formula: position size = money you accept losing ÷ distance to your stop. US$100 ÷ 5% = US$2,000.
Common mistake
Mistake: going big because you “feel sure”. Confidence doesn't change the odds. Ten 1% losses in a row sting; ten 20% losses end your account.
Key takeaway
Pick your stop first, then your size. Small, fixed risk per trade keeps you in the game long enough to learn.

A 1% risk rule on US$10,000 means risking at most... US$100 per trade1% of 10,000 is 100. That's the most a single losing trade should cost.
Stop 5% away, risk US$100. Position size? US$2,000Risk ÷ stop distance: 100 ÷ 0.05 = 2,000. If the stop is hit, 5% of 2,000 is lost: 100.
Your position size should come from... Your stop distance and risk ruleSize is maths, not mood: decide the loss you accept, then fit the position to your stop.
Why risk only a small % per trade? So a losing streak can't wipe you outEven good traders hit losing streaks. Small risk means you survive them.