The honest answer almost nobody gives beginners: it depends far more on your lot sizing and account type than on a magic minimum number.
On a standard account, a sound baseline is enough to run the minimum 0.01 lot without your free margin getting eaten on the first trade — for many gold/FX strategies that’s roughly a few hundred dollars. If you want to run smaller and safer, a cent (micro) account makes the same 0.01 lot about 1/100th the real exposure.
The mistake I see most is starting with “enough” money but a lot size that’s far too big for it, then getting a margin error on the very first trade. Curious what others here started with, and whether you’d do it differently now.