I think you should start trading with demo account and then when you comfortable then you start with real account with small capital and trade with small lot size. It is good for you when you understand every think about forex market and you capital is big then you can start with big lot size. Depend on the leverage of the account for example in 1:100 leverage $1 is equal too 0.01 lot which means $100 is equal to 1 lot and $800 is equal to 8 lot. So minimum $2k required for.trading 8lot and rwmaing funds for safety from margin call.
If any want to change leverage then lots size matter too better carefull when trading the market.